Hi susannew32,
yes, PMR is often part of a differential diagnosis with other causes. If the steroid methypredisolone if rapidly effective, it will be another clue that you have PMR.
In general people with PMR have high cortisol levels. So that's a clue in the column that indicates no PMR.
If PMR is untreated it can develop in to Giant Cell Arterietis, so I'm happy with your prescription for Medrol, especially impressive if the script comes from a general practitioner.
If you don't have a rheumatilogist, you might consider consulting one.
The small fracture at L-1 needs to be addressed for cause. Those small fractures can remain undetected.
A local priest had just such a fracture undetected by MRI and he wasn't scripted for a CT. He took so much tylenal that he ended his life in liver failure.
You are on a high short course of steroid which is a good diagnostic application. If you have osteoporosis (the fracture) you won't want to be on steroid.
That kind of fracture can cause the pain your are feeling.