Bleeding during sexual intercourse

I need help. :( I'm 20 years old, I gave birth at the age of 17, and for 3 years, i have not been sexually active.  I have a boyfriend but he's not the father of my child. We've been having sex since the past 5 months. The first time, I had a slight bleeding after. There are also occasions that it doesn't, we usually do it once a week or once in 2 weeks. The last time we did it, it was after two weeks and he penetrated deeply and vagina was bleeding, it was bright red and it's not that thick. I'm not due until next week. I didn't feel any pain either. I know I need a professional assistance but first I want to hear to know if this has occurred to other women too and what could this be so I'll know what to expect when I get checked by the doctor. By the way, i'm not having abnormal discharge and foul smell or itching. And this is the first time I have encountered something like this not even before I had a child. I'm pretty sure that the man that I've been doing it with is STI free. THANK YOU! :D:D