Thanks mrsD & Deb!
When this started, I saw several good foot doctors — orthopedists and podiatrists. X-rays and MRIs ensued, all negative. The only MD who knew what he was talking about was the podiatrist who referred me to a rheumatologist.
On another note, I am giving some serious thought to seeing a neurologist for a second opinion on my diagnosis — for no other reason than accepted wisdom says that one should always get a second opinion. In other words, I do not expect that anything will come of it, except a lot of expensive and intrusive tests.
What's worse: A grim diagnosis or a grim diagnosis that they torture you to arrive at?