I had brown-dark red bleeding 5 days after my period ended. I have not had unprotected sex and im not on pill. Implantation bleeding? Or what?

Breakthrough. It's probably breakthrough bleeding, can't say for sure 'why' over the internet. 'implantation bleeding' is all the rage online now, but it's over-rated in importance. It's not consistent and is usually not 'implantation' but breakthrough bleeding.