Why Am I Having Repeated Episodes Of Heavy Bleeding After Starting Endura Mass?

Hiii...I m taking endura mass from 15 to 20 days...in between my periods came on time but it last for 3 days and stop bleeding after 2 days again its bleeding 3 days and stop....but after 9 to 10 days again start bleeding for 3 days ...and all time bleeding is heavy...what is the reason ...Plzz reply..