Can your period starting cause you to have a bowel movement as well as gas and lower abdominal cramps as soon as it starts?

The disease entity of "endometriosis" may involve invasion of the lower intestine (colon). When the level of estrogen drops precipitously just prior to the onset of menstrual bleeding, contractions of the colon may produce painful cramping which may stimulate a bowel movement, and gas emission. Ask your GYN about oral bcp's, which will stop ovarian high estrogen production.