Kuhio98, what's the latest on this? How's Halo?
You're evidently unsure what steps to take next. I think I might be considering a 2nd opinion, if it were me. If money isn't an issue, I'd just go off quietly and get a 2nd opinion, and still have the first vet home (so as not to stress Halo with two clinic visits in the catcarrier).

I think that might set your mind at rest.

Or call a university that does extensive cat research, like we have in Sydney, there's a Uni with cat research division my vet actually liaises with all the time. He also lectures there. They would be happy to talk to you I'm sure.(EDIT: A uni in the USA I mean, it reads like I meant you should call Sydney!)

Let us know how it goes. Hugs and prayers for Halo.
TopCat