I am currently suffering from the exact same thing. Right now I am using the lotion steroid Taclonex in addition to phototherapy which does seem to help some. I am trying to avoid the oral treatments...especially the immunosuppressive options. My case is currently being looked over by a team of doctors at Princeton that have experience with this. I will let you know what they say as soon as they get back to me.
Currently taking: Remicade