Gluten is pretty easy to avoid once you get used to doing it, its in things like bread products and bread, cakes, biscuits, tinned and frozen stuff etc. Im on a gluten free, lactose free diet and Im vegan - cant get more restricted than that. I buy all of my veg fresh, avoid cakes and biscuits [there are gluten free ones available] you can try a gluten free diet and see if it suits you. It can be in wheat, rye etc
As for getting a diagnosis, I would demand a referral to see a Gastroenterologist, you can have a colonoscopy and endoscopy with biopsies to rule out any other stomach disorders.