I'd be willing to bet this little one is dehydrated as well as whatever the underlying cause of the illness is. You need to re-check your set-up as the previous post said, increase the ambient temp by a few degrees, and increase the humidity in the tank. Soaks can also help with dehydration. Most importantly, you need to get Something in him so you can get a fecal done and get him to a vet ASAP. The ensure will work for you to get a fecal. you can also use meat (turkey) baby food, which is significantly cheaper than ensure, but not for long-term use alone.
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1.0 Hypo stripe, Het RW from JL (BJ)
1.0 HypoTang from Crested (Apricot)
1.0 Tremper Albino from Petsmart (Cloud)
1.0 SHCT hatched by me! (Sunny)
0.1 Hi-Yellow Leopard gecko from Petco (Beatrice)
0.1 Stripe female (rehabilitated rescue)(Pepper)
0.1 Jungle het RW hatched by me! (Jungle Bunny)
0.1 Normal from 2001 (Freckles)
0.1 SHCT Leopard Gecko from Petco (Brite)
0.1 Tangy Mutt Leopard Gecko from Petco (Rainbow)
0.1 Stripe poss. het RW hatched by me! (unnamed yet)
0.1 RW Stripe hatched by me! (unnamed yet)
RIP Peaches, Ghost, Bill
Adopted out: Goldie, Leucy, "Q"
Hatched: ~50