i am 21 years old .i had sex about a week ago(28th sept) and had unwanted-72 pill within 12 hrs of intercourse. my date for menses is around 20th bt today(6th oct) i had a brownish dischargeat 3am bt at the end of day the discharge color chnged to red normal color of period blood and bleeding is not stopped. what may be the reasons behind it .is it a matter of serious concern?