Hi. Looks like either a thermal burn or this thing my iguana came down with last year. He was acting completely normal, eating, etc, but he had nasty weeping blisters. When we took him to the vet, they didn't find any bacteria or fungus. The vet's best guess was that it was stress induced--he had just moved to a gigantic new enclosure. I had to bathe mine in povodine-iodine every day and put silvadene (prescription from the vet) on him every day. The scarring is finally starting to go away NOW--1yr later. The vet said reptiles take a long time to heal. Take him *to* the vet, and good luck. 
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1.0 Green Iguana
1.0 Bearded Dragon
0.1 Blizard Leopard Gecko
2.1 Corn Snakes (2 Blood Red, 1 Orange Amelanistic)
1.1 Ball Python