IBS is defined as abdominal pain or discomfort, along with a changed bowel habit (such as diarrhea or constipation), for 3 months or more. The abdomen is the same as the “stomach area.”. The symptoms may be different from person to person and can include: 1  Cramps or pain in the stomach area. 2  Constipation — infrequent stools that may be hard and dry. 3  Feeling like you haven't finished a bowel movement. 4  Diarrhea — frequent loose stools. 5  Alternating between diarrhea and constipation. 6  Mucus in the stool.