The arm does appear to be bowed, which is a sign of MBD.
Please know that you cannot reverse the damage from MBD, but you can halt the progression of the disease.
Also, your supplementing isn't quite right.
The zilla spray is not formulated properly.
What you want is a calcium with no d3 powder, to be used on every feeding, a calcium with d3 powder to be used twice a month, and a multivitamin to be used twice a month. Or you need to purchase repashy all in one calcium plus, which is formulated to include all of the above, but can be used on every feeding, with no need to switch back and forth between other powders.
As im sure the weather is turning in Ohio, it may be too cold, but if you have any days where the temps are mid 70's or higher, please take him outside. the natural sun can work wonders for mbd chams.
I would also reduce the amount of handling time for now, so as not to accidently cause damage to the already weakened bones.
His cage- at his age, he can handle the 2x2x4 foot cage, and as close to being an adult as he is, will need it anyway. I suggest upgrading.
Watering- I suggest either purchasing an auto mister, or misting more often. at least 5 times a day.
If you can, try purchasing some silkworms, probably from an online seller, and try feeding those daily. they have a great calcium content in them.
Varying his bug intake is also really good for him as well.
WHen you go to the vet, ask them to do a calcium level check, this can tell you exactly where his levels are. they may just say change your supplements, or they may put him on a liquid calcium to stabilize his numbers.
IF you are unsure of his diagnosis and treatment plan, post the info here, and other members or some of our vets who are members here, can give you advice.
I hope this helps!
Good luck!