SEX!!

Does anyone seem to find sex during pregnacey painful? The last few times my partner and I have done the "wrong sided business" it's hurt me a lot. It's kind of like a really bad stitch but it's a wounded kind of feeling. It's horrible. Am I the only one with this problem? I'll be 28 weeks tomorrow (Monday) this is my first time experiencing pregnacey with a partner as my first daughter (nearly 6) father ran so I'd done it alone from the day I found out I was pregnant. It's definitely all new to me as it is for him and having his first baby.