I ended my period last monday. The same day I took an ovulation test and it said i would ovulate the next day. My partner and I had had sexual intercourse that morning, so i know his sperm would have been alive. Today, 6 days later, I started to feel a little cramping and noticed a brownish, bloody discharge. I have continued to monitor it and now it is bright red and looks like a light to medium period. I have read that implantation bleeding is very light, so i am a bit concerned.