Kathy it is a long shot because it is a very rare condition associated, in the majority of cases, with long term use of steroids, in fewer cases with obesity, but sometimes autoimmune. The physical cause is an accumulation of fat around the spinal nerve, causing compression and consequent 'neurological deficit' - neuropathic pain and mobility problems. I have it and the clinical name is Spinal Epidural Lipomatosis; if you search the web for that term you will find corroboration of this post and pictures of how it appears on an MRI. I hope this doesn't raise false hopes, but after all you are going through, all possibilities, however rare, need to be considered.

Wishing you all the best.