ugh, i just read through the story about the vet yesterday. I guess the good thing is that if a medical problem is out of his ability, he's willing to say so. Better than faking it, I suppose.
You can tell him that you have excellent resources here on the issues that high dose cats face, so he isn't expected to be an expert on it. Almost no vets are. As long as he's open to learning with you, then hopefully things could work out. Unless you have a better vet that you can move to.
The situation with Jekyll would be unacceptable to me. Even the weight loss alone is very disturbing. Until I came here I didn't realize how many people treat cats successfully for cancer. We lost one kitty, Felix, when he had a mass at the end of his stomach. The vet did exploratory surgery and when he discovered that, we let him euthanize Felix. Now I see people getting their kitties treated for cancer and they seem to do very well with many kinds of cancer. I wish I'd known that before.
As you said, the good news is that they'll do the blood draw for you so you know what's going on.
I hope your migraine is better. I'm a bit excited by the yellow test tonight! Don't keep your mom up, though, Hyde. Another night would be better for dipping lower.