If any of the following occur, call your doctor:Signs of infection, including fever and chillsNausea and/or vomiting or vomiting bloodSevere abdominal painBlack, tar-like stools or bloody stoolsIf you think you have an emergency, call for medical help right away.RESOURCES:Gastro???American Gastroenterological Associationhttp://www.gastro.org/patient-centerAmerica