External Ultrasonic Fogger
that's one example. basically you're looking for an ultrasonic humidifier that has a round output you can connect a hose or some hardware to it and a hose to... if that made any sense. run that to the top of the setup so the humidity runs down.
chams are skitzy... real skitzy. one person around can be more than cause for it not to eat... even if it's the guy who cares for and feeds it. don't underestimate that. not saying you are... since i'm not there to see for myself... just something to consider. heck my beardie has to be twice to 3 times his size and often gets skitzed when i walk by and they're supposed to "enjoy" the company. vulnerability, confidence, age, size, etc. play big roles there. you've also not had him long... and he's tiny still... he is afraid of you... no doubt! whether it's a part of the problem, like i said, i'd have to see for myself.
and yeah, fruit flies straight from the culture will most likely smell quite horrific. a new culture may be in order if it's too overpowering.