my girlfriend and I had sex (a couple minutes without a condom and then put one on) on the 5th and we thought her period was over but she bled a little bit more that night. We got to thinking that we would rather be safe than sorry and took plan B 48 Hours after. Now she is a week for her next period date and has had brown discharge the past 3 days. She is on birth control but during the time of sex she was taking an additional medication that I didn't know about that I later found acts against birth control. Do you think the discharge is just from the plan b and now her birth control coming back into play? or pregnancy.