implantation bleeding or something else?

6 days ago, I had a small bleed; it was light pink and only enough to take up a third of a piece of toilet paper. it hasnt happened since or ANY time before that. I thought maybe I was starting my period, but alas, aunt flow has yet to make an appearance. my period has been a tad unpredictable lately but I believe I'm supposed to start within the next few days or so. I'm having troubles determining whether the small bleed was implantation bleeding or random spotting? or maybe something else? I do lead a very sexual lifestyle. so pregnancy is a possibility. I suppose I was just hoping for some guidance or opinion other than my own.