You could go in for food allergy testing. I developed food allergies in my 20s, mild-to-moderate food allergies, which would cause stomach pain for hours as well as bloating, indigestion, itchy skin and the occasional asthma bout.
I can't explain *why* I so suddenly developed these allergies, but the way you describe how you feel reminds me of how I felt before I got the testing done.
By the way: I tried the elimination thing, and thought it was *dairy* because everything I ate with dairy (cheese, milk, yogurt) contained something I turned out to be allergic to (wheat, oats, rye, barley, sesame seeds, peanuts, tree nuts, soybeans). Even if I had milk and coffee, turns out the coffee was roasted with hazelnuts. Elimination is hard work, it's easier to just go get an answer by doing blood work.
Stumbled into Primal due to food allergies, and subsequent elimination of non-primal foods.
Start Gluten-Free/Soy-Free: December 2012; start weight 158lbs, Ladies size 6
Start Primal: March 2013, start weight 150lbs, Ladies size 6
Current: 132lbs, Ladies size 2
26lbs lost since cutting the crap.