What causes pain in stomach after eating acidic food (mostly), burping, flatulence, and feeling very gassy, loose stool. Happening for a few days now.?

GI symptoms. indicates a need to see your doctor. You MAY have a diet too high in acid. The symptoms are likely from your body trying to digest the food. If your doc does not find anything wrong medically consider taking a probiotic. Doctor Ohira is a good brand. Peace and good health.