I have severe pain running down the backs of both legs (from my sitting bones down hamstrings) & knees after having sex. When I sit, it's dull & not as bad, but when I'm up it is awful! It starts within minutes of finishing sex and lasts at least half a day. Have never had this problem before. I am pregnant if that makes any difference, but haven't had this issue with past pregnancies. It's taking the fun out of having sex with my husband. Is there anything I can do to avoid or at least ease the pain?