Implantation or very early AF

Emily

update:

I ended up starting my AF. It was just a week early.

My AF has been between every 28-31 days. I started spotting this cycle on CD 23 and it was very light pink and light brown. Today I started spotting again a tiny bit heavier both very light pink and light brown. I still have almost a week until I am suppose to start my AF. Does anyone know what could cause this?