Hi I Am 22 Years Old Women I Have Pcos

hi i am 22 years old women i have pcos and i am going through the treatment.. doctor prescribed me to take femilon. last month i got my period on 27th augst and i started taking those pills from 29th according to the doctor.. in between i missed to take two pills on 6th and 7th sept. and i got period again.. after the end of my period i visited another doctor and he prescribed DRONIS 30 and FORMITAL after going through all my reports. Is something serious? why did he change my pills?