I'm so sorry to hear about Buddy.

My baby had the same diagnosis 2 years ago and died on Christmas eve. Even to this day I can think about it and cry.
By the time my vet caught it, he was too far advanced to be treated successfully, so I understand how that feels (I switched vets)

Buddy is a beautiful boy and has that sweet face of a very special kitty.
I pray that you get some good news.