update:

Bumblebee passed away roughly after lunch. THere were urates that haven't been passed but as to why (including how he went from "retic nippy" to "severely weakened" in just 2 days) the vets and I are unable to ascertain.

The vet did mention that there were unpassed urates.

In any event, this has made me even more meticulous in the husbandry of my other reptiles.

For now, I guess I can rule this out due to "sudden death" syndrome.