Do a hydrogen breath test and test for food allergies/intolerances.
I'm not full blown celiac but I have a sensitivity to certain glutens. I follow The Low Fodmap diet and gluten free diet.

Hi! I have found out that sometime after I was diagnosed with fibromyalgia, that my doctor had also found out that I have a small allergy to gluten. And some breads and wheat and soy contains gluten. I have found that a gluten free diet has helped me sleep better and given me more energy in the mornings.

Hello, food allergy is not just a blood test.
They do some thest in your skin too. I had that done I really recommended if you have any allergy food.

My allergy is onion.

That means that you are not full blown celiac but have an intolerance to gluten.
So you can eat a little bit of gluten, but not to much at once. I'm the same with gluten and lactose.

Apparently I don't have allergies after several tests, but I do have reactions to gluten or anything with soap as my skin goes rough so not sure how the tests work.