We don't have synonyms for erythermalgia yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are erythralgia.
(n) :
Alternative form of erythromelalgia. [A rare neurovascular peripheral pain disorder in which blood vessels, usually in the lower extremities or hands, are episodically blocked, then become hyperemic and inflamed.]
(n) :
Alternative form of erythromelalgia. [A rare neurovascular peripheral pain disorder in which blood vessels, usually in the lower extremities or hands, are episodically blocked, then become hyperemic and inflamed.]