I've seen a Rheumatologist as was diagnosed with Fibromyalgia about 10years ago. The foot/heel pain only came after Chemo and still is the same, no bloods detected any reason for the problem, and I had them recently, plus Fibromyalgia is only what they call it after ruling out any other auto immune diseases LOL. I'm going to try an Osteo and see if they can work it out. I actually did some research and there are a couple of things that chemo cause in relation to feet...
Plantar Fasciitis http://www.mayoclinic.org/diseases-conditions/plantar-fasciitis/symptoms-causes/dxc-20268536
It mentions that collagen that cushions the foot can be destroyed with chemo. Who knows :/ M