On depo-provera spotting for 4 weeks and cramping really bad?

Unpredictable : One of the problems with Progesterone only contraceptive methods is the unpredictable bleeding pattern. Most patients on Depo-Provera don't have any bleeding at all. Some, however, can have irregular spotting or bleeding. The cramping could be due to a number of causes and should be reported to your physician and evaluated with exam and probably an ultrasound.