Your stomach may hurt after you eat if you haven't eaten in a long time, if you've eaten a particularly large meal, or if you have an ulcer, tumor, or other mass that is not protected from stomach acid by mucus within the stomach. Stomach pain after eating is most commonly caused by the normal contractions/motions of the stomach as it churns and breaks down food with stomach acid. If you have damage to the stomach or a mass of some sort, these motions can aggravate that point of tenderness causing additional stomach pain. Gas is also a common cause of stomach pain after eating. An antacid or fizzy drink may help you belch, releasing the gas and discomfort.