Light pink spotting

flor

So guys I took plan b on Aug. 13 a day before my fertile days unprotected sex but he didn't cummed inside me. So after 5 days I bleed for almost 3 days 18-20 after that I'm having stretchy mucus and even cramps that lasted on 28 and now I'm spotting like that is this implantation or still the effect of plan b I also test a pt and it says negative