Is Taking Duphaston Advisable During Menstrual Cycle?

Hi! I have PCOS. I am taking duphaston (2pills) from 15-20day. In the first cycle my period came in the 23d day. And now that I am on the 17th day I have some drops while taking duphaston. Is that normal? Should i stop it? I am trying to conceiving and i am veryy concerned. I am 31 and I also have a 2years old boy after taking duphaston but only once to occur period that was abcent for 5 months. Now my gyn told me to get it in all the cycles till i get pregnant