Pain during sex

Me and my boyfriend have been together for 6 months now. I realized after the first couple times we had sex i would experience pain that would kinda shoot through to my uterus area, and then after I would feel/look a little bloated. I figured this would go away over time but it's a constant thing. It's not always that bad though which is why I've never asked a doctor. Does anyone else experience pain during sex similar to this?