Woos & a-rooos, Phred,
Ease up on yourself, you took him to the vet as soon as you realized that something was really wrong. Our pups are soooooo good at just going along like usual, even when they're having serious issues. And we all go thru that guilt - I'm sure we've all said "if only I'd gotten (fill in the blank) to the vet sooner" at some point.

We'll keep paws crossed & send sibe vibes for Smokey.
And here's a big ole' ((((hug))))for you, Phred!