Brown Redish Discharge

I had unprotected sex Saturday night but he didn't finish inside of me. Since then I've been seeing in my panties brown reddish discharge I'm also on the pill but my family doctor told me not to take all the pills just 21 each one every day then for one week 7 days not to and then continue. I've been taking birth control same time everyday like morning before school but he said it doesn't really make a difference if I take it 7 am and sometimes 8 or 9 am as long as I take it every day. Help!