It sounds like you have gastritis. For me, when my gastritis flares up, it is a burning feeling (kind of like what rubbing alcohol feels like when you pour it into an open would, but it doesn't go away in seconds like the open wound does and takes several hours if not days to ease up). It can be excruciating, and really scary because it is so intense. Can cause vomiting just because of the pain. Prilosec doesn't work fast enough. Zantac (generic name is Rantidine) will ease the pain within about 1/2 hour.
Stay away from NSAIDS (like Advil, aspirin, Aleve, etc.) ... they can damage the stomach further and cause it to bleed, which could be life threatening.
My gastritis is caused mainly by eating foods I am intolerant to. When I first went gluten free, I had many intolerances pop up (I was probably intolerant to them before but just didn't realize it because of an overwhelmed immune system). It may just be one food bothering you, or several. Odds are, it is dairy, eggs, soy, corn or nightshades (potato, tomato, peppers) because those tend to be the ones most people wind up being intolerant to without realizing it. Besides gluten, I have IgA responses to dairy, eggs, soy, corn, nightshades, chicken, pork, beef, tuna, rice ... I had the IgA testing done by stool test from Enterolab (wound up with IgA responses to everything they tested for, EXCEPT oats and tree nuts). Because that nixes so much food, I still eat some of the ones that bother me the least periodically, but make sure to very consciously omit the ones that bother me the most ... still have to eat SOMETHING. But I am strict to avoid gluten.
Over time, some of the foods stopped causing the gastritis to flare up, or at least not as bad. So try strictly avoiding dairy, eggs, soy, corn, nightshades, and NSAIDS for a couple weeks, just to see if your stomach feels better. Try some Zantac to ease the burning you are getting right now. Then add those foods back, one at a time for a few days or a week each, to see if it bothers your stomach, so you can narrow down which might be the problem (could be all, but this way you could see which bother you the worst).
Cross Contamination/Eating Out:
Also make SURE you aren't getting gluten cross contamination. Maybe someone is double dipping from a gluten food into your gluten-free food. Don't share the same butter, peanut butter, or other condiments that get double dipped. Squeeze bottle condiments should be OK. Do not share toasters, cutting boards, colanders, wooden spoons, or blenders/mixers. Microwave is okay, IF people cover their food dishes when cooking ... otherwise food splatters that don't get cleaned up in the microwave could cross contaminate the next thing in the microwave.
At potlucks, go through the food line first, or bring your own food (keep your portion separate the whole time). Check that seasoning mixes are gluten free. I really don't trust other people's foods at potlucks, except perhaps for fruit and veggie trays. You never know if they clean up all the crumbs before attempt making something gluten free, or maybe they made a cake or bread before so there could be flour in the air. I just bring several gluten free items to serve for my contribution but before arriving have a personal portion in a separate container for myself so I don't go hungry. Unless you know specifically how someone cooked a turkey, I'd avoid it ... if they used one of those oven cooking bags, the instructions say to use a tablespoon or two of flour in the bag before putting the turkey or other meat in, so you could get cross contaminated that way. Stew prepared by someone else, I'd avoid unless you know what seasoning they used ... many people use stew seasoning mixes, of which many are not gluten free. Avoid the green beans at potlucks and buffets ... many use beef bouillon to flavor them, and most bouillons are not gluten free (if you need some bouillon for your own cooking, Hydrox small envelopes are safe, just not the other types, like cubes).
Check any medications or supplements are gluten free (Advil Liqi-Gels and their other liquid forms are NOT gluten free, but with gastritis you need to avoid Advil anyway).
Ensure any candies you eat are gluten free ... check with the manufacturers (all Hershey miniatures they say they cannot guarantee are gluten free); Heath, York, PayDay, regular Kisses, full-size Hershey bars chocolate or almond, full-size Reeses are safe (except for special holiday ones). Mr. Goodbar and Krackle are not safe. Twizzlers are not safe. Most jelly beans are OK.
Soy sauce may not be safe (most use wheat, read the label). When I eat out at a Chinese or other Asian restaurant, if I am allowing myself soy, I ask for gluten-free soy sauce (La Choy is gluten free, though usually isn't served in restaurants; Kikoman is usually what is in restaurants, so you have to ask for the gluten-free type of Kikoman). If they don't have any, or if I am avoiding soy, I just ask for no soy sauce and for them to season with salt, pepper, and garlic. Make sure you don't order anything with breading, and if it is something with a sauce only get something that uses cornstarch to thicken (would be a clear, white sauce). If, because of language difficulty, you cannot get them to understand, just say no sauce and only use salt, pepper, and garlic. Rice noodles should be OK, but if it is on a buffet, ask for some from the kitchen ... I have to do that at Hu-Hot because they put the rice noodles right next to the wheat-based noodles, and people are always using the same tongs to serve themselves from both, or are dropping the gluteny noodles into the rice noodles.
McDonald's french fries are NOT safe, even if they use a dedicated fryer ... they use a beef flavoring that has gluten to flavor the fries; most fast-food chili is NOT safe (Wendy's, Sonic); most fast-food grilled chicken is NOT safe (Burger King, McDonald's, etc.). For the big burger chains (i.e., McDonald's, Burger King, Wendy's, Hardee's, Steak & Shake), the only safe thing is the ice cream, some of the burger patties without bun (not all are safe because some will use a specialty seasoning with gluten), and salad without the grilled chicken or croutons, and some breakfast items like basic eggs and bacon. I do not trust the apple/yogurt/granola packets from McDonald's due to the granola not being gluten free and them all being packaged in the same container ... too easy for the granola to cross contaminate the yogurt. The only safe things from Sonic are hot dogs without buns and ice cream. I totally avoid places like Subway or other delis or pizza places ... cross contamination is too likely with the flour in the air from the baking, or the crumbs from the food preparation.
Nothing at Taco Bell is safe, except for tostadas and two of the rice bowl options.
A lot of steak houses with a specialty seasoning are not safe (i.e., Texas Roadhouse, etc.) ... just order it only seasoned with salt and pepper.
At many of the chain restaurants, a lot of the vegetables you would expect to be safe are not. Make sure to ask for their allergy menus to see which are safe.
Frozen vegetables ... READ THE LABELS; some are not safe, not just because of seasoning or sauces added, but because some use wheat to keep the vegetables from clumping together. Wal-Mart brand has been bad about this.
If you are a Christian church goer, make your own communion bread ... let me know if you need tips on how.