Have fever. body pains and restlessness and headache and upper abdominal pain more likely on the left side.

Doctor can evaluate: Many things are in the upper abdomen: stomach, pancreas, liver, small intestine, gall bladder, large intestine, abdominal muscles, etc... One's doctor can check to see if this is a flu or something else. The stomach itself and the spleen are in the left upper abdomen. Pain in the right upper abdomen, plus symptoms that occur after eating, can be due to gallstones or other gall bladder disease.