Why do i get really bad headaches during and after sex? it is horrible right on the back of my head and stays that way for what seems forever.

:-(: Post-coital headache though unfortunate is a well known phenomenon. Assuming you don't have any secondary etiology for your headaches there're no evidenced based studies to prevent this other then abstinence; which is not realistic. Some preemptively takes nsaid but I do not know how effective this is. Make sure you get checked out by a neurologist first before assuming this is post-coital headach