Spotting? Implantation? Random occurrence?

Jennifer • Mother to a beautiful little girl! TTC #2 ❤️ POAS addict! Oh and a loving wifey ?
Monday (12/1) I started spotting and I continued to do so until Wednesday (12/3) and it was a brown/dark brown in color... AF should start (12/14) could this have been implantation bleeding or just a random thing? 
Side note: I do not know for sure when ovulation occurred.