Pains and period period twice in one month i've stop bleeding but, my legs are aching and my stomach is cramping badly i am sexually active

You : You do need to be checked by a physician. Have you had a urine pregnancy test? If not you do need to have one. The cramping is concerning and could represent "dysfunctional uterine bleeding" which is irregular periods, but can also represent an infection. Your leg aching could represent that you are anemic from heavy periods. Please have this checked. If you start having more pain, more bleeding, or become light-headed or faint then you must be seen as an emergency.