Plan b side effect or period


Okay ladies... I had unprotected sex with my husband during my ovulation window. The next day about 20 hrs later I took plan b. Fast forward a week of cramping nothing serious. Last night I started to spot, very light nothing a panty liner can’t handle. Now it’s more red but still light. My period is suppose to be 7 days from now. My question is, this bleeding from plan b side effect or period coming early.