Why dose your bowls move more on your p.m.s?

Pelvic congestion: Part of the premenstrual syndrome is the pelvic congestion which includes of pelvic walls lined by muscles and peritoneum & pelvic organs like intestines, bladder, in addition to uterus and ovaries. The intestinal congestion caused increased leaking of fluid across the increased wall, also causing incresed stimulation of the nerves supplying the intestines thus causing more bowel movements in pms.