thanks for query.
your problem is known as polymenorrhea in which menstruation
occur in less than 21days time.
you have not mentioned your age and are you married or not,or sexually active or not?
polymenorrhea treatment depend upon its cause so first you should rule out your cause by some gynae than treat the cause.
causes are-1)stress2)endometriosis3)chronic PID4)menopause5)malnutrition6)ant. pitutary gland disease7)STD
so first detect the cause than treat the cause accordingly.