A month came twice menstruation, how does the color black return a responsibility little

According to the description, consider may not menstrual cramps caused by vaginal bleeding. May be caused by ovulation bleeding, or because there is a gynecological disease caused by reasons such as uterine fibroids, endometrial thickening and other reasons. It is recommended to go to the hospital to do color ultrasound examination, can be clear about the specific cause.