get hydrotherm! it will maintain both humidity and temps with night drop. or for just temperature you can get any thermostat , i just got one for 20$ off ebay for my incubator, not sure if it has night temps drop, but i don't need it
how big is he now, you were asking about him in august, so by now he should be adult size, he needs something other then crickets ( nightcrawler, roaches), whatever is happening with your frog is because of unstable conditions, too hot, then too cold, do you dust crickets?