I'm on CD 21 and have a very short cycle usually between 22-26 days. Yesterday after BDing, when I went to use the bathroom I noticed pink and brown spotting. It was only CD 21 and have never had a cycle this early. I had a little spotting today but not as much, now it's gone and I just have cramps. Anyone have implantation bleeding this late in the cycle? I tested before I saw the spotting but got a BFN...Help.