Why does my stomach get upset everytime I eat?

Gallstones? There are a number of causes of upset stomach after eating. These include gastritis (inflammation of lining of stomach), an ulcer (either in the stomach or the upper part of intestines), gallstones, food sensitivity/allergy, or reflux disease. It's always a good idea with stomach symptoms to see your physician. Hope you feel better soon!
Gastritis. Good question. Sounds like you need to see a GI specialist. Remember that it could also be reflux, an ulcer, food allergy, lactose intolerance, food intolerance, medication-induced, etc... Could be a simple solution but a million things could cause GI upset.