My Husband For The Past Month Almost Has Had A

my husband for the past month almost has had a rash starting in his head itchy and burning feeling but slowly moved down to his face all over his cheeks and neck and now started to move onto his arms but remaining in the other places as well. we have been to a skin and cancer nurse practitioner she tested for psoriasis and lupus and the test came back negative. There have been no answers that they can give us one doctor even said he had never seen anything like this before.