Could be red leg but if he isn't lethargic maybe not. Or its early red leg.
Another possibility is a thick layer of stuck shed skin on his leg.
And another possibility is a broken leg or some other injury.
The vet will figure it out.

I would suggest supplementing his diet with some high calorie variety such as an occassional pre killed fuzzy mouse, Rosey red minnows, nightcrawlers, Horn worms or a commercial diet such as Nuance Pacman food, Zoomed Pacman food, or Hikari Pac Attack. A diet of strictly crickets no matter how well supplemented and gut loaded may still lack certain micronutrients.
I would also suggest removing some of the substrate so that he can't burrow completely out of sight, and inch or inch and a half deep. Just enough so his head and eyes can be poking out. This will help you to better monitor him and his condition without disturbing him


I would strongly recommend getting rid of the white heat lamp right away
Bright lighting may harm their eyes and dry their skin as well as cause them to hide more.

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