Your tank does look a little bit to open. I would also recommend changing the bedding to repti chips. The bedding is probably not the problem though. What size tank do you have him in? The tank and cave appear to be small. If he can comfortably fit in those, he’s probably not 2 1/2 yrs old. I imagine that he should be bigger. I would recommend getting a kitchen gram scale. That way you can track his weight. What have you been trying to feed him?