What Should I Do? I Took Postnor 2 After Sex

what should i do? I took postnor 2 after sex the same day.few days later i started to bleed and today is the 4th day. I normally see my period 11th of every month and sometimes it changes..pls tellme on what to do.if am ok..though he ddnt come inside of me but one cant be too sure thats y i took it