I've had mild cramping for 5 days and no period. My last period was 2/28/12, I'm irregular but not by this long. Preg test says neg. What could it be?

Failure to ovulate. Give it another week. If still no period, recheck pregnancy test. If at that time, still no period, recheck preg test. If still neg and no period, contact your health care provider. If your period arrives in the next week or so, just continue to keep track of your periods. Read about pcos.