What Causes Cramps,brown Discharge After Having Unsafe Sex Despite Taking Postinor 2?

I had unprotected sex 7days ago with my boyfriend, I took postinor 2 immediately and the other after 12 hours. 2 days later I had mild cramps and some reddish brownish discharge... After around 5 days of that sex, my vagina started to itch though not that severe. Is this itching means that my hormone are unbalanced in my vagina due to the postinor 2 or is it mean am approaching my periods? Am worried please help