What Are The Side Effects Of Depo Provera Injection?

I just got off of the depo shot at the begining of july i ALWAYS have severe cramping everymonth had it injul and aug but not in sept. my cramping usually lasts from the 30th of the previous month to the 7th and this month i havent gotten anything couldi be preganat? UI took a test is said negetive but i have all the symptoms could this b a false negative??