Neither a neurologist nor a rheumatologist had any idea. An orthopedic surgeon suggested a calf strain, but I disagree.
Essentially, my right calf is very sensitive to pedaling motions, such as playing drums or piano or driving. At times the ankle will itch deeply in a way that can't be scratched, and often accompanying this is an extreme soreness and heaviness of both legs that goes away gradually when I sit down. This is only an occasional thing. I can often run short distances at least with no problem.
My calf will also start cramping when I'm at rest sometimes, primarily after exercising. Also there are occasional fasciculations, which I know are typically nothing to worry about but might be worth noting.
I'm 32 and have relatively low blood pressure and am in decent shape overall -- in fact, before all of this started I was active in rock climbing and karate -- so claudication, while a possibility, has not been investigated.
Anyone have any ideas? I have trouble with upper back pain as well, for what it's worth.