What if it is a gluten problem? Reactions can be very confusing - I don't think it safe to dismiss getting tested because you don't react as strongly to certain foods. There are people with Celiac Disease that have little or no noticeable reaction to gluten, but the intestinal damage is happening. After it is removed they often become highly intolerant of gluten with severe reaction - your body is used to consuming/dealing with gluten - that could change if you completely remove it.
So I am pretty sure it is not gluten - but should be something that is high in real ale, wheat bears, staropramen, UK bread but low in french bread (in france), pizza in italy etc. I have thought yeast or hops of some kind but I am not sure. I guess this might be slightly off topic for this forum but if anyone has any pointers or ideas it would be great.
With the drastic difference between consuming beer and other types of alcohol I think it wise to be tested for both Celiac Disease AND Food Allergies. It is possible to have celiac OR allergies OR both. Getting the Full Celiac Blood Panel is important before removing gluten as it gives the best chance to be accurate, because Celiac Disease is an autoimmune reaction, not an allergy. If you remove the gluten, there is no reason for your body to produced the antibodies being tested in the blood tests.
Good Luck to you