pain during sex??

I'm 18 years old and my boyfriend is 19, we've been together about 7 months. We've been having sex without problems for at least 6 months, but recently, during some positions I have been experiencing pain during our sex. It's only when his penis touches a more anterior part of my vaginal wall and I get a pain similar to a bruise or a cramp; not anything sharp, like a cut or anything. More like pressure.

I spoke with a woman at our health services on campus at our college, and she asked if I had been experiencing any other pain, to which I said no, and no discharge, or blood, or pain during other positions, or even just being normal throughout my day or pushing on my pelvis or stomach.

She said to wait it out and not have sex for a while and that it could've been from a full bladder or because my period is next week.

I was wondering what you all were thinking. Has anyone else experienced this?