How long does breakthrough bleeding last?

I started the pill on the first day of my period 2 weeks ago from today, I had my normal period for a week, but the bleeding didnt stop, it just continued as breakthrough bleeding (so breakthrough bleeding has been going on for a week now). How much longer will it last? Also, yesterday, my doctor switched me to a stronger pill because of the breakthrough bleeding and I'm not noticing any changes.. if switching is meant to stop the breakthrough bleeding, how long after the switch until the bleeding stops?