PLAN B BLEEDING VS IMPLANTATION BLEEDING??

I took the plan b Jan 4, hours later after enjoying the night with my husband. We both decided it’ll be best to hold off on a pregnancy after forgetting to use a condom. Anyways, on Jan 10-11 I was bleeding heavily and I knew that would happen so I dealt with it. But today, Jan 16 I’m spotting. Like every time I wipe myself there’s a tinge of blood. My question is, is it normal to ALSO spot even after a week from plan b bleeding??? Or Is it implantation bleeding? I’m mildly cramping as well. Has this ever happened to anyone and they under up being pregnant?? Please assist!