Diverticulitis, also called colonic diverticulitis, is a gastrointestinal disease characterized by inflammation of abnormal pouches¡ªdiverticula¡ªthat can develop in the wall of the large intestine.[1] Symptoms typically include lower abdominal pain of sudden onset, but the onset may also occur over a few days.[1] There may also be nausea, diarrhea or constipation.[1] Fever or blood in the stool suggests a complication.[1] People may experience a single attack, repeated attacks, or ongoing "smouldering" diverticulitis.[2][4][5]

Reference
Wiki: Colonic inflammation