It could be stomach or gall bladder
. Go to health food store and buy some good quality strong digestive enzymes. There are ones to help with stomach digestion. And there are others to aid the liver
, bile, gall bladder and pancreas
). Take these right after your meals, dont drink too much fluids with your meals as this dilutes the stomach acids that are trying to digest your meal. Dont eat late at night, slow down and chew more thoroughly and avoid heavy greasy foods! Be nice to your stomach or it wont be nice to you. And dont just cover it up with drugs/ meds.