Could be that you are allergic to Gluten (Wheat, Rye, and Barley). Look on the web for Celiac disease. You may not have full blown Celiac but have a sensitivity as I do. It was very upsetting to discover this about myself but it gets easier with time and I feel so much better.
Abdominal distention or bloating can be due to indigestion or sudden increase in fibrous foods. For details,visit abdominal distention.