Hello Sir/mam My Marriage Is On 17 Fed Nd On

Hello sir/mam my marriage is on 17 fed nd on that day is my period also I consult my doctor they gave me familon pills for 21 days .I have doubt that after 21 days when period will come. Nd this medicine can be taken as regular for 21 days it could not be drop in between nd I more question pills taken with milk necessary nd also it works na ...was it safe