Implantation bleeding?

I had one little spot when I wiped, 4 days before my period, it's been 24hrs and I haven't bleed again. I normally dont spot this early, and I count the 4 or so days of spotting i normally get as my period on this app. No nausea but I am soooooo moody, and my breast hurt. I hope it's just pms.. any thoughts?