Had my period at 7dpo?!

So I ovulated late, CD 20, at 7dpo I had brown/pink spotting thought maybe implantation then it got red and brown lasted 6 days which is not normal for me I usually have 3 days max of light bleeding like very light. This was the heaviest period I've had. And it slowed down to pink spotting around day 3. Still today I have very light pink when I wipe. It came 7 days early. I should be getting my period today! At 14dpo. I'm going to Wal-Mart today anyways and I'm going to get a 88cent test just for the hell of it. I know it's pretty rare that if be pregnant and bleed like that right? I mean how can a little one implant when my lining is shedding?