What Causes Brownish Discharge In The Mid Of Menstruation Cycle?

What are the chances of getting pregnant if 1. the guy wore a condom. 2. he "went" twice. one time, both times when he was nowhere near the area. 3. it didn't feel like he went in all the way, or much. 4. used plan b about an hour or two after. I ask because i heard about implantation bleeding and about 6 or 7 days after the event, i noticed brown discharge and it's been going on for about a week. help!