Had sex right after my period, after a week, i see pink/brownish discharge.implantation bleeding? took plan b yesterday&before i got my period

Typical with Plan B: Plan b essentially disrupts the normal menstrual cycle by blocking or delaying ovulation. That it is how it works and why it is so different than a medical abortion. Irregular bleeding after taking Plan B is not rare. Always check a pregnancy test after using Plan B and see a doctor to start a better form of birth control. You need a better plan than this.