Indigestion, which is sometimes called dyspepsia, can make a person feel uncomfortable or full in the upper belly, and it often causes bloating and gas. Usually, it's not something to worry too much about. But if someone has really bad stomach pain, fever, throwing up or sees blood in their poop, it could be a more serious issue like gastritis, ulcers or problems with the gallbladder. If someone's not sure why their stomach hurts, it's a good idea to see a doctor for a check-up.