Had sex march 20 the condom broke so i took plan b two hours later now it's 5 days before my period and i have some brown discharge. could this be implantation bleeding or a side effect from plan b ?

Likely plan b: Plan B does upset normal menstrual cycle and it is likely that the bleeding is due to drop in hormone levels. If you miss your normal period by 4-5 days, do a home pregnancy test. If the result is negative repeat the test 4-5 days later unless you get a period by then. Use first morning urine and follow the instructions for the test carefully. If you do not wish to be pregnant, use contraception all the time, every time. You may consider implanted contraceptive, or IUD. Practice safe sex if you have sex.