If you're at the point of seeing a specialist you'll have tried most of this, but just in case:
First of all, try all the GPs in your surgery. I've never had much luck until recently, turns out one of ours really knows skin.
If he's prone to infection try dermol, both the cream and the wash.
If it's very dry try epaderm at night - it's really thick like Vaseline and a brilliant moisturiser.
DD has a couple of stubborn patches that we were using hydrocortisone on constantly. GP prescribed a stronger steroid (can't remember the name sorry, begins with E) to use for a week or two to fully clear it and then use at weekends to maintain it. It's been very successful for DD, I'm hoping to try with my own post pregnancy.
We were discussing this with friends recently. The frustrating thing is every doctor seems to have a different opinion, and everyone responds to different things. If I used the regime a friend's son is on I'd be covered from head to toe, but it works well for him.
Lastly, regular very thin layers of cream work much better for me than slathering it on, and clean PJs every night help when it's bad so it's fresh cotton against my skin, not last night's soaked in cream.