Problems regaurding 'feminine issues'?

i have been on the 3 month depo birth control shot for almost 2 years now, but for the past 9 months or so i have yet to get my period. i recently got off of the shot for about 2 months, and still no period. i have been cramping horribly and my stomach muscles and all tightened around my uterus area. slight spotting has been happening for about 2 weeks now but its always very light and goes away within a half hour and doesnt happen again for a few days. im also having very bad pains throughout my abdominal area and discomfort when i lay down. im bloated as if i would be on my period but nothings happening- any ideas what could be going on?