Been on depo-provera for 8 months i've been spotting but no full period until days ago. i have bad cramps & my next shot is @ the end of feb. what's wrong ?

Side effects of Depo: Sometimes it can take several months for cycle regulation with depot provera (medroxyprogesterone). As long as the bleeding is not heavy, it's more of a nuisance. It's designed to lighten or completely eliminate menstrual flow in most women with normal bmi. If pelvic pain or cramping persists, she a gynecologist to consider an evaluation for endometriosis.