Pain and discomfort when having sex

I've missed my last period and have a few other symptoms, sore breasts... night nausea and throwing up.... ect. even though I don't feel like I'm pregnant but my boyfriend seems to be convinced that I am. I'll take a pregnancy test in a week or less to know for sure. I did notice a very tiny spot of blood a week ago. Only noticed from wiping after peeing. But for the past few days when we have sex it's very uncomfortable for me. He said its like the head of his "member" is hitting something inside. It does not feel good, to the point having him stop. Has anyone had this happen to them or know what it is?