Really need help! TMI

So I took an opk and got a positive on the 23/24 of September and a negative one on the 25th. According to glow I was supposed to start my period yesterday, oct 5, instead I got really light pink spotting with what looked like little mucous boogers? I only spotted a little then it stopped. I've been watching my cycles very carefully since ttc June to now. And I have NEVER spotted before. I also have very mild cramping and sore nipples. Could this be implantation?? Any ideas what this could be?