bleeding during and after sex??

So back story i’ve had sex before my hymen’s popped or whatever so i have a new bf and we started having sex a couple time and after we finished there was lots of blood i thought it was my period and then i did start my period but we did it again after my period and i was bleeding a lot again does anyone know why this is happening i’ve had a couple bv but i went to the doctors and role care of it but idk why i could be bleeding bc i didn’t start my period he was also not bigger then the last guy