i bled while he was fingering me??

why did i start bleeding after my boyfriend fingered me? he used two fingers and his nails are cut. but i started bleeding a lot and now i’m swollen down there, all throughout when he was fingering me i didn’t feel anything hurt me. we were doing this for 6 or 7 min but it was dark so we didn’t see. i’m pretty scared right now, idk what to do.