Implantation or AF?

Yesterday when I went to the bathroom and wiped I had some brown discharge (not a lot). So I put on a panty liner thinking it’s my Af coming since this app predicts my next cycle starts today. Nothing was on the panty liner next time I went to bathroom and when I wiped there was nothing. Today it was the same thing. Wiped and had brown discharge (not a lot), places panty liner on and by the next time I used the bathroom there was nothing. Could this be implantation or is this AF coming?