Pain during sex (tmi)

Ive been having pain during sex the past week. Im not sure what it could be. I don’t know if it might have to do with the fact that my period is a week late. Does anyone have any ideas of why I could be having these pains? It usually hurts when my boyfriend is trying to go in and it takes a while before he can get inside of medie to the pain and for some reason it’s been tighter than usual. I also have an appt with the doctor next week and I will ask about this. Plus I took a pregnancy test since I am a week late and it came back negative.