Enough of your symptoms are similar to mine to make investigating hereditary neuropathy (CMT) worthwhile, as Kitt suggested. And yes, I have undergone periods of rapid deterioration after what seemed like a slow and steady pace. In one case it was precipitated by taking Tricor for high triglycerides. Several medications are highly toxic for CMT.

I began with a clumsy, odd gait as a child, high arches, walking on the outside of my feet. Progressed to numbness in my toes in my 30's which is now up to my thighs. No discernable reflexes. Balance problems, and muscle weakness in both hands and feet and legs. Visible wasting and severe pain in legs. Like you I have no access to family history, but do some research and see if you recognize yourself. Neuologists hate the diagnosis, there is no treatment, but some comfort in knowing what you have.

Best of luck.