Infertility

One night me and and my boyfriend had sex and not even 2 minutes later i had to stop because i couldnt really move and i was having horrible sharp pains that were constant in my lower stomach and back i was getting hot flashes and i was nauseous i couldnt even pull up my pants i took a pregnancy test 3 days before my period was suppose to be here and it was negative now im 4 days late on my period. Help?