What Causes Rashes On The Scalp And Around The Mouth?

My husband started breaking out in a rash on his head scalp area and around his mouth on Monday. Tuesday it was all over his head and spread to inside his mouth and ears. He was running such a high fever the ear wax in his ears liquefied and poured out his ears. He has been itching uncontrollably and has major discomfort. Tuesday he went to dr they said he could have hand foot and mouth disease and put him on amoxicillin. This morning he was broke out in hives from head to toe. Some blisters some just bumps. From this morning to tonight it has worsened. He was about to go in this morning and get a steroid shot which helped with itching however this is just getting worse.