Implantation or early AF?

Alright, so my AF isn't suppose to start until the 7/23 & yesterday 7/17 I started spotting dark brown cm along with some cramping but nothing like my AF cramping and today too but not as much & much lighter brown but its there every time I wipe, not sure if AF is getting ready to start earlier then expected.. glow says I ovulation day is 7/8 which means 7/17-7/18 I would have my implantation which is today. I'm just confused. I'm pretty regular 28 day cycles & 6 day AFs. My nipples are sore, my face is breaking out like crazy, been moody. Just curious what you ladies think!