I had sex with my boyfriend on Thursday, November 21. I took plan B the next day, friday, November 22. Exactly a week later after having sex, (Thursday, November 28), I have found red/brownish blood on my underwear. This is the only symptom I've gotten from the plan B. Did the plan B work or not? I suspected my ovulation time to be on Tuesday, November 26, and it's been 2 days after.. Please answer.