HELP!

The 12th or the 13th I ovulated..I ovulated a few days later this cycle...the 19th I had woke up and there was spotting of dark brown on the sheets...wasn't heavy at all wasn't enough to use a tampon like little drops...every now and then..but by that night it had already been a day since it started had no symptoms of my period coming AF was due on the 20th bleeding was only a day implantation or period? I'm currently not bleeding at all and also in my left boob it's been really tender