HEAVY bleeding during sex

So, my boyfriend and I had sex two nights ago and he suddenly stopped and looked at me and said: "Did I hurt you? I think your bleeding." But I didn't feel any pain and didn't think much of it, so we continued. When we got up though there was a LOT of dark red blood on the sheets. When he went to wash them out he realized he had a 6 mm cut on his penis. So it was probably his blood and mine, because something sharp got inbetween us without us noticing. He stopped bleeding a few minutes after, but I bled all night and there were still traces of blood when I wiped throughout the day. But again, no pain at all.

When we had sex yesterday, I started bleeding again for an hour or so. He didn't this time.

Should I be worried?

Oh, also my period is definitely not due yet, neither am I ovulating, and it can't be implantation bleeding either. So I suppose I'm hurt (which I think I would feel) or it's something else. Any ideas?

Thank you, ladies.