I thought his eyes look a little sunken also. Make sure you mist him real good - 3 times a day for at least 5 minutes each time. This will help to get him drinking again so that he can rehydrate himself. Also make sure you've got a dripper in his cage. Use live plants in his cage to help with the humidity.
He's a beautiful animal. I'm sure he'll do much better now that you have him.