Implantation bleeding ?

My boyfriend and I had sex while I was ovulating and it was on 3 of the days that I would be high risk to get pregnant. It’s been 5 days since the first time we had sex when I was ovulating. My period is supposed to start in about 10-12 days. I woke up this morning and there was what appeared to be a darkish blood in my underwear and I was having some mild cramping. Is this implantation bleeding ?