Plan b spotting

I had unprotected sex a week ago (we stopped before he was even close). I took a plan b right after and yesterday I had some spotting. It was a rust color, then a bit pink and finally brown. I went to the bathroom today and there was no more spotting. I’m really worried that this was implantation bleeding. According to the app (I know it’s not accurate) I was fertile that day we had sex. He didn’t finish though. And I took a plan b. So was this bleeding I experienced implantation? Or just plan b side effect? *i read the pamphlet that came with it, but online it also says this could be a sign of pregnancy. I’m so worried.