Erythromelalgia

I am interested if there is anyone who has successfully treated this condition.
I am trying to assist a family member who has this condition. She was given this diagnosis today. Previously it has been called burning feet syndrome.

Symptoms:
Intense, rapid onset of red hot burning feet, bilateral symptoms.
Feet become red, inflamed, sometimes hot to touch, sometimes not. Pain is intense, burning, can wake her up, lasts for anything from 15 mins to an hour or more, then subsides.
Most often, occurs in afternoons but also at night. No particular time, no obvious causes. Not influenced by exercising or resting.
Better for nothing on feet, better for putting in cool water for short time.
No obvious maintaining causes, no co-morbidities.

I have looked at acute remedies and tried obvious candidates. I have tried arsenicum and sulphur. This is a person who responds well to arsenicum constitutionally. There has been no response to any remedy, either better or worse.

Very interested to here if anyone else has seen or treated this condition and if there are other factors such as nutrition which influence this condition. Many thanks for your help.