What Is The Hard And Sharp Thing Inside My Vagina?

I'm a 25 year old woman, 5'4 120lbs, clean medical history. In a relationship with a 25 year old man, 6'0 and 195lbs. We've been having sex for nearly 6 months and he mention that its always hurt him. He says he hits something inside me that's hard and feels sharp. Also that he feels he gets scratched well having intercourse. We both have been tested before we started having sex and are std free. Neither of us have experienced this with previous partners. What's causing this? and Can it be fixed?