What Causes Heavy Menstrual Bleeding With Blood Clot While On Camrese?

Hi I just started birth control a little over 2 months ago (camrese a substitute for seasonique). Since the beginning of the third month I have been bleeding pretty heavily and had what I am assuming was a blood clot come out with my period. I haven t started the yellow pills yet which represent when my period is suppose to be. Is this normal? Should I keep refilling this prescription?