Anytime you’re dealing with the nervous system, it’s going to be frustrating. You must be patient and trust the client because this might be some of the worst physical pain they’ve ever dealt with. I can speak with experience on both sides of this.
I would first ensure the client has the most comfortable footwear possible. You also need to know their pain threshold, though I understand this condition can bring some real sharp, intense pain as well as burning and numbness.
You could try elevating the toes slightly and direct the load bearing to the heel, and see if that avoids causing pain. Or try a donut-shaped cushion around the area.
Though I’m not a doctor, but a steady dose of NSAIDs and rest are typical for this condition. Otherwise, injections or surgery might be the only relief.
All in all, I would avoid most or all weight bearing activity on the foot as the pain for most is simply intolerable. And watch out for severe compensation such as turning the foot outward and using leg adductors.
I would suggest swimming and a lot of mat and band work. Machines are also an option. For the upper-body you can still do pretty much anything, just don’t do it standing. Try seated and progress to half-kneeling.