Celiac disease can be diagnosed at any age. It is an allergy to gluten. Unfortunately for us with GP, almost all the symptoms are one in the same. Even more so for me as I also have Multiple Sclerosis. I also have IBS and Ehlers- Danlos. Fun times. There are blood tests for celiac but false positives and false negatives are not uncommon. From my understanding, the small upper intestinal biopsy is the only true tell and that is done endoscopy. I am going through that in a couple weeks. Though not a doctor, I say try the gluten free diet. Stick with it for a few months and see how you feel. If you feel better either stay on the diet and or see a doctor for tests. Unfortunately, much of a gluten free diet is about fresh fruits and vegetables, a no no for those of us with GP. I suggest seeing a dietician at the very least and FIRST before going gluten free. No need to get sick due to malnutrition. GP is bad enough on that front. I wish you luck.