What Causes Fluid Discharges Instead Of Menstruation With Cramping, Excess Bowel Movements?

Hi I am 19. I Have had regular periods since I was 12. I had it last on May 4th and I was supposed to get it on the 7th of June. I have had mild cramps and when I did believe I had gotten it, it turned out to be clear fluid. I have been extremely hungry and pooping a lot. I took 2 pregnancy tests and both said I am not pregnant. So other than pregnancy...what would be the cause?