What Causes Irregular Periods While Lutrozole Medication?

hello doctor my age is 23 years my last period is 30th of september
i have pcod problem and doctor told me go for pcod profile in that insulin level in is high so doctor gave me a glycomet 850mg two per day. my next month period time is 30th of october . but 17th day of my cycle bleeding was started doctor gave me lutrozole 2.5mg for consive. why my period was come so early. will you give me the clarification.
and one more thing is 4 months back i had one miscarriage in that time also i used lutrozole2.5mg