When I had problems as a kid, my doctor had me stop eating dairy for 2 weeks. Really no tests they could give besides time, so I would suggest a trial run before you go to the doctor and track the results. By god, I felt 100x better by the end of the 2 weeks, but I missed cheese too much and lied to the doctor and my mom. "No, I feel the same..."
Now I'm off regular dairy again for the baby, because she was already having problems with it. As soon as I went off it this time, the swelling in my feet went away and I had energy for the first time in months. Even my allergies are better. I feel 100x better again, but the Dairy Queen commercials...

Haven't gotten ice cream from there in months, but now that I can't have it, I want it.