Ridiculously bad aim

[LilyPad]

It does sound like a vitamin deficiency of some sort. Have you tried small amounts of vitamin A, like, once a month? What kind of calcium are you using? Calcium+D3 is what you should be using and it should be tossed every 6 months. Mealworms are not a good feeder. They are high in fat and chitin and low in nutrients. If he is unwilling to eat crickets, the worms (night crawler pieces especially) would make for an excellent feeder. If you have normal temperatures and humidity, then he shouldn't be trying to hibernate.

Vitamin A - https://www.amazon.com/Repashy-Vitam...vitamin+a+plus
Calcium - https://www.amazon.com/Rep-Cal-SRP00...eywords=repcal
Multivitamin - https://www.amazon.com/HERPTIVITE-Mu...eywords=repcal

There are other brands out there, but I have tried several and these seem to keep my frogs in the best shape. My toad doesn't burrow in completely, but does what you said, just kind of digs his butt in a bit.