Emergency contraception

I took an EC pill on the 18th which was two days after my last period. Then had sex again a couple days later and the condom failed but didn't want to take another EC pill twice in the same week. But now on Sunday almost a week after I took the pill I started to bleed. Does the pill make my period start early? I've been bleeding for about three days now and I've also been cramping and somewhat nauseous.