I think the most important question you need to ask yourself is, "Do the Depo Medrol shots help you?" If they do you have a major part of your answer. I only lasted 8 years in pain management. Initially I had two epidurals which did nothing to relieve my pain. When I was offered a third (all in the period of six months) I asked my doctor what his reasoning was that after two failures a third would work? At the time the literature I read stated a person should have no more than three in one year. He could not give me an answer and never mentioned epidurals again.
But if your shots are giving you relief weigh the benefit against the risks. After all, it is all about quality of life! Good luck to you, Gwen