Ok i am TTC and AF is due in 4 days according to my regular cycle and <a href="https://play.google.com/store/apps/details?id=com.glow.android">Glow app</a> predictions. I had sex regularly thru my fertile window. I had quite a bit of brown spotting today when I went to use the bathroom and wiped. Could this be implantation bleeding or my period trying to come early? Been having sore breast and back pain.