There are test kits available (urine test) that can tell you if you consumed gluten in the last ~24 hours, but without that, there is no way to be certain. Eating out in restaurants in the primary source of contamination for most celiacs.  Many people with celiac disease, especially those who are in the 0-2 year range of their recovery, have additional food intolerance issues which could be temporary. To figure this out you may need to keep a food diary and do an elimination diet over a few months. Some common food intolerance issues are dairy/casein, eggs, corn, oats, and soy. The good news is that after your gut heals (for most people who are 100% gluten-free this will take several months to two years) you may be able to slowly add some these items back into your diet after the damaged villi heal. This article may be helpful:    

I've not tried them, but making your own anti-inflammatory juice shots at home can be a great way to support gut health while ensuring ingredients are fresh, cost-effective, and tailored to your needs. Many store-bought options (like Thistle’s) are convenient, but DIY versions allow you to control ingredients and avoid additives. Some powerful anti-inflammatory ingredients to include are: Turmeric & Ginger (known for reducing inflammation and soothing digestion) Aloe Vera Juice (supports gut lining and reduces irritation) Pineapple (contains bromelain, an enzyme that aids digestion) Leafy Greens (kale, spinach—rich in antioxidants) Beetroot (supports liver detox and reduces oxidative stress) A simple gut-healing shot could blend ginger, turmeric, lemon, and a pinch of black pepper (to enhance turmeric absorption). If you’re dealing with celiac or gut sensitivity, homemade juices also eliminate cross-contamination risks. Just be mindful of FODMAPs if you have IBS-like symptoms. Have you tried any specific recipes? Blending or cold-pressing could impact nutrient retention too—some prefer slow juicers for maximum benefits.

It sounds like an exiting plan, and there is a lot of great naturally gluten-free foods in the Caribbean islands, Mexico, Central America, etc.

If you’ve been strictly gluten-free for several years, your tTG IgA level of 13.6 (within the normal range of <15) is generally a good sign, as it suggests no significant gluten exposure or ongoing immune response. However, some celiac patients on a gluten-free diet may still have low but detectable tTG IgA levels due to minor cross-contamination, slow healing, or other factors. Your recent symptoms (Bristol 6 stools, abdominal pain, nausea) could indicate accidental gluten ingestion, but they might also stem from other issues like IBS, food intolerances, or gut dysbiosis. Since your GI is concerned about more serious conditions, an endoscopy with biopsy could help confirm whether there’s persistent intestinal damage or another underlying problem. While gluten exposure is possible, the slow normalization of your stools suggests it may have been a transient issue. Continuing to monitor your diet and symptoms while following up with your doctor is wise. If no other cause is found, a trial of an even stricter gluten-free diet (e.g., avoiding processed foods or dining out) might help. You may want to also try eliminating oats and milk/casein if you can't get the levels lower.  For people with celiac disease hidden gluten in their diets is the main cause of elevated Tissue Transglutaminase IgA Antibodies (tTG-IgA), but there are other conditions, including cow's milk/casein intolerance, that can also cause this, and here is an article about the other possible causes:    

I am surprised that your doctor would not diagnose based on sight? I was diagnosed with dermatitis herpetiformis but the biopsy came back negative. The dermatologist said that can happen as the disease was not active at the time, but it was classic dermatitis herpetiformis in his opinion especially since I was already diagnosed with celiac several years prior to the dermatitis herpetiformis flare up. Like many on the dermatitis herpetiformis threads I suffered from itchy burning lesions on my elbows. Very painful when I was in the shower. Dermatologist prescribed dapsone gel 7.5%. There is a pill option but I wanted to first try the topical gel and it eased the burning sensation and after a few weeks got rid of the visible signs of dermatitis herpetiformis. I only use it when my dermatitis herpetiformis is active. I recently had a flare up but had the dapsone gel available and it quickly eased the itchy burning skin on both elbows (which is where I usually get dermatitis herpetiformis). I was also told to avoid iodine and of course gluten.