8 days ago me and my boyfriend were having manual sex. he came on my hand and i wiped it off on a blanket, then about 10 minutes later i stuck my finger inside my vagina to see if i was still bleeding because it was the last day of my period. then i realozed what i did, and from being scared i took plan b 2 days later. today i found really dark brown discharge. im scared, is this just a plan b side effect?