The length of every female's menstrual cycle is different. A normal cycle is 21-35 days from the first day of menstruation to the first day of the next period. This varies especially during puberty so someone can have more than 1 period in a month. Continuous vaginal bleeding or bleeding when you are not menstruating can be caused by things like cervical cancer, miscarriage, abortion side effects, STIs or as a side effect of family planning. If this happen go to a health centre for review.
Attribution: Straight Talk Foundation