S.,
It could be a severe B Complex deficiency, Get him some good vitamins at the store. Liquid B's are available. Because this climate is so humid it really creates mold and fungus. The B vitamins help correct this. He could also be dehydrated.
There are very good liquid multi-vitamins at the health food store. A good brand is Natures Plus. If he drinks sodas these types of drinks will increase the dehydration. Get him to drink lots of good water.
I read your responses and just want to repeat that skin problems are started with a B complex deficiency that will be helped with vitamins and corrections to the diet. Sugars of any kind, soda, fast food, tend to feed the problem. Clean up the diet and do the vitamins and it takes four months to correct this deficiency.
Those are my two suggestions.
D.