I've finally received initial results from my MRI from my family doctor. Several problems in my spine and spinal cord including areas of demyelinization and stenosis, but most if not all of those were not new and hadn't changed much since 2008. There has been some additional growth of bony abnormalities on some vertebrae, including to the point where (as I understood it) at least a couple may almost be fusing, but that didn't seem to worry him too much.
What was both new (in terms of extent) and worrisome was the almost complete degeneration of the L2-L3 spinal disc. That's probably the reason for my sore, stiff lower back... and leg spasms when I get out of bed or out of chairs. When I asked him if that could be the cause of my recent decreasing mobility, he said he didn't know. He did say that surgery for such problems is very rare, and they would have to be very sure that it truly was the cause of my mobility problems before they would do anything. In other words, I'm probably going to have to live with it, with pain-killers and appropriate physio the best that modern medicine can do for me.
I hope that my neuro has something a little more encouraging for me when I see her after she gets back from her sick leave.