scared shitless

I had unprotected sex during my fertile window. (Yes, I get it I'm fucking stupid) my fertile window ended Friday. (Jan 20th). Today (January 22) I started bleeding a very light pink. I'm assuming it's implantation bleeding. I'm not supposed to get my period for 10-11 days. 
So I guess I'm asking, I'm having period like symptoms but they are a little different. Like, cramping, but more like a egg dropping cramping. And almost constant? Headache, back ache, and fatigue. Does it sound like implantation bleeding?