Hey Sylph, sorry to hear of the dilemma. Did the vet recommend a immunity boosting supplement? Powder or liquid that could be used in conjunction with feeding? The discoloration in the scales does look suspicious but i would start with a deep cleaning of the enclosure (even though i know you said you are on top of that). Are the paper towels solid white and not the "printed " variety? Then try a 50/ 50 concentration of betadine to water on a paper towel or cloth to wipe down the areas of concern coupled with a slight boost in the ambient enclosure temperature. Monitor the progress and consider contacting the vet for this.