Implantation bleeding

Hi.

I have a really frustrating and common problem. My daughters dad and I had unprotected sex during ovulation. One week later I was spotting. Day 1: a pinky coloured blood that was only visable for one wipe. Day 2; nothing. Day 3,4 and 5 the same as day 1. Day 6 however I have a light-normal period bleed. I am still not due for a few more days. Took a pregnancy test and it's negative. I have no patience and am getting frustrated. Has anyone had a similar experience, If so what was your outcome?