Clotting heavy bleeding after sex..living with POS

after I cumm I bleed. it normally last about 15 mintues then I pass a few clots. I bleed about 5 hours total then everything is back to normal. I have periods but I don't bleed. my periods consists of the linning passing in a light brown discharge. My doctor said that was normal and if I was not concerned about not blleding doing my periods then there is nothing to worry about. But the bleeding after sex is new and it is starting to concern me.