No change eh? Ok. Normally snakeys come out of an overly moist hibernation with lesions of necrotic scales which are caused by bacteria, (commonly called blister disease) but this doesn't look like that.
My second thought, and the reason I asked about worming etc. was a Yeast infection or Staph. infection. Sometimes treatment for coccidia, worms, etc. can decimate a reptile's beneficial digestive bacteria which gives yeast the chance to multiply in great numbers.
This internal yeast infection could spread, through feces, to the skin of the snake and take on a fungal form basically digesting the scales/skin. It's a longshot, but not unheard of. This occurance is becoming more common, and in the bearded dragon, is fatal.
However, this is all just conjecture by an armchair herpetologist, so don't take what I say as gold. 
Your vet should be able to sample the site and determine whether it's yeast or staph or whatever.
Has his condition improved since you started applying the topical treatment?
DAN