Blood in my vagina

Hello everyone,

I'm not experienced so I don't know much about sex. I was with a guy yesterday and things got very heated. After all of that (we didn't have sex, still a virgin) but we were very close to, I had some blood on my vagina, very very little. Where did that come from?

Edit: I'm not close to periods or ovulating. The blood doesn't look like it's a scratch it's a little bit more than that.