As far as the supplements go, it totally depends on what kinds you are using, what you are gut-loading your feeders with, how much natural sunlight your guy is getting and what fruits and veggies he is eating himself.
At the most, your guy should only be getting Ca+D3 every 2 weeks (unless you are using one of the supplements with low levels that are made for daily dusting). If you are not using the daily use supplement, you should be giving calcium (plain phosphorus free) every day lightly dusted on the bugs you are feeding him.
Overdosing on vitamins and D3 can be just as dangerous as the under-supplementing can be. If you are using a daily powder like the Repashy stuff, stick with that. Otherwise, if I were you, I would quit with the D3 for about a month, increase the hydration as much as possible including showers.
I hope all works out well for you with this guy.
Have you tried to see if there are any vet schools around you? How about a zoo? Sometimes these kinds of places will help you out too, especially if you don't have a good exotic vet close.
Good luck... Keeping my fingers crossed for you two.