Guys. Ok.

So typically my period is a little irregular but in the sense that I have loooooong cycles. Sometimes I'll totally skip a month or month and a half. I have unprotective sex frequently. I started my period on the 14th of last month (17 days ago) and it ended on the 18th (12 days ago). Today, I got home to go to the bathroom and there was a faint blood stain in my underwear (that are light pink so its hard to really tell). I wiped and it was suuuuper light pink. So I put on a pad and went about my day. Then I realized...I JUST stopped my period 12 days ago. I took and ovulation test last night and it was negative. This clearly isn't normal. Does this sound like implantation bleeding? Anyone had something similar happen? I know these posts are a dime a dozen. I just need sound advice.