Why am i cramping & why do i have white semi thick discharge

There is absolutely no way for me to keep track of my periods . i , for a couple years , tended to have one a year . i was on depo for about four months and the whole time i bled for about 85 % of that time , so i got off of it . that was when i was 16 , im 20 ( birthday is 02-26-90 ) , and the last period that i recall having started the middle of november 2008 and last til the middle of december 2008. i havent had another since then , i started noticing some changes with my body february 2010 ( my breasts were sore & my stomach bloated after i ate ) which in fact i found out i was pregnant . in march 2010 i ended up miscarrying . ------- [ so this being a little about my past health issues ] ------

Now , im having some cramping & white semi thick discharge . my breasts are not sore but i tend to bloat a when i eat .
does any one know what may be causing this ? i have taken a pregnancy test about a week and a half ago ( maybe ) and it came back negative .. could this be pregnancy or something else ?

Please help