"... I'm trying to see if I can get him into a vet either
later today or tomorrow morning,
but needless to say my regular vet is booked ..."

I'd ask to speak to at least the Senior Receptionist or Tech -
and REMIND him/her that your Tubby is a REGULAR Client;
you feel Very Concerned about his condition;
and you'd Appreciate an "emergency visit" TODAY!

We've had a crisis or two over the years;
and Doc Mike goes out of his way to "get us in" when there
is a real need to be quick...
He's worked through lunch, stayed late, whatever it takes -
If I'm worried - so is he!

Several times we've been the "fill-in patient" -
on "stand-by" to dash over on a moment's notice
when they get the last minute cancellation.

I called on a Monday morning - NOT a good day to "squeeze in" -
for Boots. Was told to "bring him in NOW; we'll fit him in - somehow."
Doc actually "worked" him in 3 times that day - a few minutes at a time
between scheduled patients.

I'd suggest the Tubster be seen by his "Regular White Coat" -
just because that Vet is familiar with his condition.

Call em up - and don't be afraid to lean on em!

/s/ Phred
.