That is exactly the same as what I am going through. I was a day late. Period was light, but still a period, for 1 and a half days, then it disappeared and came back slightly for half a day and then since then it has just been a few spots or diluted blood. It is a week since it started and I have cramps :S I am only 20 so I don't know how likely it is that it is cysts for me.
I think that you should go get checked out you may have a cyst. Best of luck.