help me decide

I took plan b a week ago while on my fertile window(not ovulation day) and today I experienced spotting. I never spit in between my periods and this didn’t happen the first time I took plan b(this was my second). It was bright red at first with itty bitty clots and now it’s pink. Can someone help me define whether this is implantation or just the plan b...?*12 days from my period. Haven’t had any cramps. Just nausea and spotting. I’m taking a test tonight.