A week after my period i start bleeding again with large clots, my stomach hurts. i always have what seems recurring bv? what could it be?

A multiplicity: Of possible issues. Make things easy on yourself and go see a gynecologist. Rather than trying to self diagnose, let someone with extensive training in the normal and abnormal physiology and anatomy of the female reproductive system be your guide. You need an exam and imaging, probably tests of blood amongst other things to answer these questions. Call and make an appointment ASAP.