There are many reasons why menstruation stops and comes back after a few days, such as physiological reasons like ovulation bleeding and pathological reasons like vaginitis and cervical lesions. 1. Ovulatory bleeding: occurs about fourteen days before the next menstrual period, belongs to the ovulatory bleeding, generally less bleeding, short time, once in a while this phenomenon is normal. 2. Pathologic: (1) vaginitis: if there is vaginal inflammation, due to vaginal congestion and edema, it may lead to symptoms of irregular vaginal bleeding. (2) Cervical lesions: such as cervical polyps, cervical erosion, cervical cancer, etc., when sex touches the lesions, there may be irregular vaginal bleeding. Menstruation stops after a few days and then come back may also exist other reasons, it is recommended to consult a doctor in a timely manner, improve the relevant examination, under the guidance of a professional doctor to clarify the cause of the disease, targeted treatment.