Diverticular Disease begins with the presence of divertula (a little sac of lining that bulges out through the muscle layers of the intestine) which is called diverticulosis. This is not a problem unless it becomes inflamed (diverticulitis) when it may cause such symptoms as severe cramping pain, nausea, constipation, fever, or chills. X-rays or procedures such as Colonoscopy may be needed to diagnose this disease.