Welcome to Connect, @jraw.
This must be so difficult for you and your son. I wonder if @badtweety2005 @jackee or @kam2005 have any thoughts to offer?

Here's some information from KidsHealth.org although I suspect you've already done a lot of research http://kidshealth.org/parent/medical/allergies/psoriasis.html

How long has your son had psoriasis?