hi, me and my girlfriend had sex july 28-30th. She had her period August 2-7 i believe. I did not cum in her, I used a condom and made sure I came outside even with it. She got her period again August 26-sept1. we have sex the day her period ends (used condom again) there was a moment where i went in without one and most likely didnt precum. still. We took plan b that day to make sure all is well. she never got any side effects before (we've taken it before) 5 days after taking Plan b, she just wiped her vagina and noticed a tiny kernel sized blot of blood on the tissue. what does this mean? is this a plan b effect or something I should be worried about?

please! answer