Very Bad Shed - what to do?

[PitOnTheProwl]

There's no undertank heater at the moment as it's hot outside - I use lamp at nights, but he may be burned like a week or 10 days ago when I used it last time.

What are you using to regulate it??

How about I show you what you are going to have a couple years later...............................

[(disabled.900)]

Any advice on how to treat burn?

[Daybreaker]

Any advice on how to treat burn?

Judging by the pic in your first post I would be at a vet asap. In the meantime as others said: take him off aspen and onto paper towels.