After intercorse I feel like I have period cramps but I don't know why... it doesnt happen all the time but lately it has a lot.
"It is possible that during sex, you tore or bruised something inside. Or, it is also possible that you have something going on in there like a cyst or something that would be irritated by sex. Some women also experience painful sex that is related to a problem with their hormones. Many women on birth control have painful sex as a side effect of the BC. The only way to be certain is to see a gynecologist. It sounds like it could be severe though, so I definately recommend seeing your doctor!
~Jessica"
--Quoted from http://www.womens-health.com/boards/sex/869-bad-cramps-after-sex.html
make sure your not pregnant because during sex if your pergnant if he goes in deep he may irritate your cervix which is closed and afterward it may feel like cramps you may wanna bee your obgyn
May be best to make an appointment with a gynecologist to figure it out...Take care !!
