Contraceptive injection

Daisy
So just over a month ago I got this injection. And the nurse said I will have very irregular periods for the first injection and then stop having them after that. For the past two weeks now I've been on a strange kinda period. It started off slightly normal. It was brown for about four or five days and then the red blood started to come. This continued for about a week or just under and now for the past 5 days it has been brown but quite light and Idk when it's gonna stop. Has anyone had this experience when on the jab and if so what happened to you? Thanks!