Implantation or period? HELP!

I had unprotected sex with this man who claims has a vasectomy, and he pulled out all the time but I still took plan b within 24hrs. Today is CD 24 and in the morning I wiped and I saw light red. Then I got home and saw tiny blood cloths and some dark brown blood. So I put a pad on and this is what I get but now I’m not bleeding anymore. Is this the start of my period because of plan b or is this implantation? I was reading and i thought implantation was only light red dots but it can be dark brown too and not only spotting. 😥