Little pockets develop in your colon over time. If something gets caught in one it festers and causes infection and excruciating cramps and pain.I GOOGLED the following:

Signs and symptoms
General signs and symptoms of colitis include intense pain, tenderness in the abdomen, depression, rapid weight loss, aches and pains within the joints, fatigue, changes in bowel habits (increased frequency), fever; swelling of the colon tissue, erythema (redness) of the surface of the colon, ulcers on the colon (in ulcerative colitis) which can bleed, mucus in the stool, blood in stool and rectal bleeding. Diarrhea may present itself, although some forms of colitis are constipation so the stool and bowel movements can appear normal.

Other symptoms may include: gas, bloating, indigestion, heartburn, reflux, Gastro oesophageal reflux disease (GORD or GERD when using the alternative spelling esophageal), cramps, urgency and many other uncomfortable aches in the gastrointestinal system.

Common tests which reveal these signs include X-rays of the colon, testing the stool for blood and pus, sigmoidoscopy, and colonoscopy. Additional tests include stool cultures and blood tests, including blood chemistry tests. A high erythrocyte sedimentation rate (ESR) is one typical finding in acute exacerbations of colitis.

Sounds familiar, no?