What is his set up like? Some time small overlooked issues with husbandry may be drastically affecting your leo.
What size enclosure? What are the temps? How is it heated? How are you reading temps (digital thermometer, temp gun...etc)? What is the substrate? What have you been using for supplements? How many hides? Is he housed alone?
The temps should be around 92 in the "hot spot" and an ambient of 85-88 in the rest of the enclosure.
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0.1 Bearded dragon
0.1 mexican kingsnake
1.0.2 Leopard Gecko's
0.0.1 Rose Hair Tarantula
1.0 BTS
0.0.1 Reverse Okeetee Corn
0.1 Bullmastiff
4.1 Cats