What Causes Early Menstruation Like Bleeding After Taking Unwanted-72?

Hii, I had unprotected sex on the 6th day of my period for the first time...nd had taken for the first time Unwanted 72 on 70th hour i.e on 3rd day. After 7 day of taking the pill am getting the period ..the first day it is little bleeding and den in 2nd day it is normal bleeding as i used to get in my periods. now it is d 3rd day. So am little concern is it my regular period or just side effect of the pill. Because iti s too early for my regular period..Kindly suggest what should i do?