Strangest thing ya know?

Hi, my DSO and I have been TTC now for a month and I think we got it. My period is now late but this afternoon I had some cramping on one side and like 2 drops of pink blood. The cramps were so faint and only lasted about an hour and I am no longer bleeding. What was that all about? It was the strangest thing. I am really fertile too and so is he, I just had my last baby 6 months ago and my period has been normal. We used an OPK and we had full sex right during all my fertile days. Whats going on?