Abdominal pain may be caused by any of various minor ailments, especially indigestion. However, you should suspect appendicitis if there is persistent pain and rigidity in the lower right side of the abdomen, especially if accompanied by fever and nausea. Never give anyone displaying these symptoms a laxative, an enema, or food. Have him lie down until the doctor sees him. Never apply a heating pad. An ice pack may be used if pain is severe.