pressure and bleeding during intercourse

Hi I'm 25 years old and have been sexually active since I was 19. Up until recently sex has been fine. I started seeing my boyfriend 2 months ago and we just started having sex. I feel pressure whenever he's behind or I'm on top. Sometimes I ask him to stop or slow down. It doesn't hurt its just uncomfortable. We usually use a condom and I'm not on birth control yet. I have a gyn appt. In November because my doctor is booked. Last night during intercourse I wason top and felt pressure but because I havent seen him in a week I blew it off and continued. I asked to do another position and I saw bright red blood on him and coming from me. This has never happened before. And I thought my period was early..its not due for atleast another few days. About 10 minutes later it stopped. I had some cramps but it went away after the bleeding stopped. I'm am very concerned and if anyone can help me that would be great.