Cramping after sex?

I'm 7 weeks pregnant, everything seems pretty normal so far, after me and my boyfriend have sex I seem to cramp for about 5 minutes afterwards. No bleeding or spotting just hurts and eventually goes away.. Is this normal? Does anyone else have this? This is my second time pregnant but when I was pregnant with my son 6 yrs ago my exhusband was deployed so I didn't have sex at all, so I have no idea what to expect.