I was treated for std but been bleeding for 3 weeks non stop real heavy and lots of clots nothing like my normal period what could this be? What shoul

Vaginal bleeding. Any abnormal vaginal bleeding requires professional evaluations. There are too many possible causes to even guess. It might or might not be related to your recent STD diagnosis. Return to your gynecologist and/or the doctor who treated you for the STD. Do it soon.