Gayle King CBD Oil This is the cause why endometriosis ache is frequently disregarded while it happens in accordance with the girl's menstrual cycle. Endometriosis ache affects 5% to 10% of girls and one of the main causes of continual ache in girls. Aside from menstruation, pain is also felt at some point of ovulation, urination, and bowel elimination. There are different conditions that can cause pain in endometriosis as ache is caused by formation of adhesions and infection inside the pelvic hollow space.