Slow healing foot wounds with Erythromelalgia?

My husband got a dose of ancef in the hospital and had a reaction which they called Steven Johnson syndrome. Subsequently he started having these flare-ups with his feet where they would turn bright red and swollen and even turned purple and blue. The only thing that would give him relief was a cold foot bath and a fan. Since then he's had these wounds that have been on the tops of his feet from the antibiotic reaction and blistering. They have been very slow to heal. Has anybody else had any experience with wounds coupled with the erythromelalgia?