My Boyfriend Told Me He Experienced Slight Pain And Scratches

My boyfriend told me he experienced slight pain and scratches on his penis after we had intercourse. I do not have an IUD and I have never and do not have an STD. I did notice that during certain positions it felt like he was hitting something, which I assumed was my cervix. Once we changed positions slightly it was better. I did have some pain (soreness) after. Any idea what inside me could be doing this?