My daughter has a Bearded Dragon and he is weak, eats little and sometimes does not eat, could it be that the light in his glass cage is too hot. She feeds him crickets with vitamins. We took him to the vet and he is now on a special diet for a couple of days. What else can we feed him please

My daughter has a bearded dragon and he is weak, has significantly low appetite and sometimes does not eat at all. She feeds him crickets with vitamins. We took him to the vet and he is now on a special diet for a couple of days.

What else can we feed him? Could it be that the light in his glass cage is too hot? Please help me, any suggestions would be greatly appreciated.