Ditto 70%cocoa. Also, I would give the duckling swim therapy. Warm water, 85F or so, just enough to float in because it has no oils yet, and for maybe five, ten minutes at a time, till it seems tired.
The idea is to get weight off the foot but opportunity to exercise and strengthen the muscles, perhaps let some of the tendons stretch.
Thiamine, I have heard, may help leg problems.
I also would do a mini-massage of the leg and foot, as much as might be tolerated for short periods of time (a minute or less).