I have pain in the left or right side of the belly ?

Doctor can evaluate: If one has some uncomfortable tummy or flank pain, and is normally in good health, plus is not pregnant, the possibilities include: appendicitis (usually lower R tummy), diverticulitis (usually L tummy), gallstone, kidney stone, constipation (crampy on L), tumor, intestinal infection, urinary tract infection, etc... A person with more than brief, mild pain usually needs a doctor's evaluation.