I'm no vet, but it looks like a burn to me. I would not use the neosporin/bacatrin is said you were. That's stuff is bad for scales. Get him to a vet. I believe what you're going to get for a burn is called silvadine (something like that, can't remember) cream.

You definitely need a thermostat. You can't run heat pads unregulated. As far as they hydrofarm, it will work, but they suck. I had one on a qt tank, and hated it. Herpstats however, are awesome. That's what I'd recommend.