Is this normal?

I've been having some random stomach virus that they're trying to figure out whether I have a parasite or not just a lot of diarrhea and some other stuff. But I just started a new birth control this will be my second pack of it and today I just started randomly started  bleeding it was just some breakthrough bleeding I've had today is that normal or is that something I should be concerned about?? I just got off my period a little over a week ago!