General Cycle Questions

Destini

Me and my husband had unprotected sex on the 17th and he didn’t pull out. I took a plan B on the 19th. I just started bleeding out of nowhere. Yesterday I had a little nipple tenderness and today I had light stabbing pain near my c section scar but it stopped. Idk if this is the plan b working or just an early period. Can someone give me some insight on this please?