I Got A Depo Shot On December 4th Of 2015.

I got a depo shot on December 4th of 2015. I have not had a shot since. I bled for 3 months, then it stopped. I had a longer lasting period on March 21st that lasted 9 day. As of April 8th, I noticed I was bleeding lightly. Now I notice a foul odor in the blood. It smells very fishy, and I have pain in my lower abdomen, through my back. Near my kidneys. What could be the problem?