Perhaps adding some wild salmon oil to his diet will help? Do you have the heat on yet? Perhaps it's getting a little dried out?
You could try Mane N Tail ProTect. You can usually find it in Farm Stores OR it's available from Amazon. It's antimicrobial and anti fungal, in case he has something going on. Just use as directed (you have to dilute). Then rinse rinse rinse rinse and rinse again. Only use conditioner on his feathers and maybe chest. And then rinse a LOT again.
Hope he's feeling better soon.