Causes of Erythromelalgia Based on TCM:
Although erythromelalgia is usually caused by extreme heat or friction many times there is no identifiable cause. Most of the patients who have idiopathic erythromelalgia are over the age of sixty, which means there is no known cause. When people who are younger than sixty years of age may have the symptoms of erythromelalgia because of an underlying autoimmune disorder like diabetes or lupus or they could have a genetic blood vessel disease. Erythromelalgia has also been correlated with neurological conditions like multiple sclerosis. Although it could happen it is rare that it can run in families and have a parent be a carrier of a specific gene mutation and passing it down to a child.

Some of the possible causes can include:
Age
Being deficient in nutrients like Pantothenic Acid
Excessive sweating, especially on your feet.
Heavy metal poisoning
Fungal or other infections
Neurological problems
Wearing socks or shoes that are too tight for too long period of time.