Well, Ivy didn't eat the vet.
Maestro sounds hyperthyroid to me... classic symptoms - weight loss, vomiting and his age is a sure sign.
I am guessing that would show up on a CBC?
That's good that Ivy didn't rip you or the vet apart.
The vet called and nothing really conclusive.
That's good that there isn't anything showing up in Maestro's tests.