Carazette side effects?

i have been on carazeete for nearly 3 wks now and got my period 11 days ago and they have been soooo heavy and soooo painfull. I still have them now and tehy dont seem to be getting any lighter??anyone any idea if this is normal when on carazette?i had to come off teh combined pill a few months ago becuase i had a constant period for a few weeks so the doctor recommened to stop taking it