Inflammatory bowel disease (IBD) is an umbrella term used to describe disorders that involve chronic inflammation of your digestive tract. Types of IBD include: Ulcerative colitis. This condition causes long-lasting inflammation and sores (ulcers) in the innermost lining of your large intestine (colon) and rectum Crohn's disease, one of the main forms of IBD, usually causes pain in the lower right side of your belly. The other main form, ulcerative colitis, leads to pain in the left side of your belly. If you have IBS, you probably have pain or cramps in the lower half of your belly.