Where does abdominal spasms come from?

Several sources: Abdominal wall spasms usually come from unaccustomed abdominal muscle exercise (extra sit-ups, etc), internal abdominal spasms usually occur in the muscles of the GI tract, sometimes from pockets of gas or firm stool that stretch the bowel, sometimes "twitchiness" of bowel wall associated with irritable bowel syndrome. All are painful but cause no permanent damage.