Why am I bleeding after sex?

My boyfriend fingered me for a while as we were getting into it. It hurt a little bit but eventually it started to feel good and he would finger me for a bit, we would stop and make out, then he would go back to it every so often. Well after we were done I noticed I was bleeding.

This happened with my ex boyfriend as well once or twice, except he would finger me past the point where it felt good and one time I started to like gush out blood from my vagina.

Pretty sure I don’t have any STDs as last boyfriend was the only sexual partner I’ve ever had (we never even had full intercourse) and he was tested as clean for everything.

New boyfriend has never been with anyone else so I shouldn’t have anything from him.

Is this normal? What are the causes? What can I do to stop it?