Help!! Please!!

Marie • 18 | Chinese/Russian mixed | 👻
Ok, first of all I'm not a virgin. Lost it in June and I've been with several guys since then.
So my FWB and I managed to have sex 2 nights ago. 
I say "managed" because when he went to put it in it was extremely painful but I figured I would adjust and I kind of did.
I went over to his last night again and we ofcourse wanted to have sex again except we didn't. When he tried to put it in, I was in so much pain 😣 he stopped and told me we didn't have to have sex and just talk & cuddle instead. I insisted he try again but good lord it was so f*cking painful and I started bleeding a lot aswell. I was almost crying. 
He stopped, cleaned me up, changed the sheets, got in bed and just cuddled, gave me butterfly kisses & made me laugh until I fell asleep. But that's beside the point...he so sweet & adorable tho 💕
Last time I had sex was 2nd Oct (different guy), I "managed" to have sex with my FWB on the 11th Oct.
It's not that long ago and I was fine then... wtf... ugh the human body is so confusing 😓
My vagina still hurts abit from last night. It just didn't want to adjust. 😒
But anyways, can anyone explain what is wrong with my vagina?
Oh and also I'm on birth control aswell