--but the most common ones are slow, progressive farthest-extremities-first-and-then-upwards-over-time, and your progression sounds a bit different; enough so that I suspect, as Dr. Smith does, something that is more compressive in nature, possibly in the lumbar or sacral spine/nerve roots, which can casue exactly the same sorts of symptoms (one reason that pinning down causes of neuropathic symptoms is so difficult).

And, the dull, achy feeling, with sitting being problematic but sleeping being easier to tolerate--lower back compressions tend to ease in a recumbent position--does tend to imply that sort of etiology.

I think an MRI of the lower spine is in order (if you can get it).