What Causes Recurring Itchy Rash On Arms And Legs?

My friend has had a rash for a couple weeks. It was treated in Toronto and was clearing up. He has now come to Florida and some of the rash has flared up. It was on his arms, legs and scrotum. It has now reappeared on his scrotum and is accompanied by a burning sensation and itching and he says it is somewhat painful. I am giving his email address for any response. Thank you.