I had digestive problems as well. I know this has nothing to do with digestive problems, but it turns out that I tested high for mercury in my body. I had mercury poisoning from the silver fillings in my mouth. This causes all sorts of problems, including digestive problems. Do you have any fillings?
As scarlet37 suggests with the gluten allergy reference, ask to be tested for Celiac disease. It runs in my family and has much the same symptoms you describe. In the meantime, if you want to test the hypothesis, try cutting out all foods containing gluten (wheat, rye, barley, etc). - google it and you'll find lists of foods and ingredients that contain gluten. If you successfully cut out gluten, then within a few days you should start feeling some relief. Here are a few references to get you started:
Unfortunately, if it is celiac, the only treatment is a completely gluten-free diet. Even a little bit of gluten can cause symptoms to return. Good luck!
Perhaps you have a food allergy? Maybe you're allergic to gluten - many people have this problem too. Google it :)
good Luck