How about trying the 'Feliway collar' with Vita?

Oscar wears a really stretchy collar (came off in a playfight with Cole once, so it is stretchy enough to not choke him AT ALL), and at breakfast time, I shake the Feliway and put one little shot into the collar.

Took Oscar and I a couple of days to get adjusted, but now he just keeps on eating while I do it!

Also - spray JUST enough to create a squirt - not a whole 'puff' of spray.

See what the vet thinks - maybe 3 x a day might be enough. And using the Feliway this way, it lasts FOREVER.

I hope Sparkle responds to antibiotics and this turns out to be just one of those weird bugs that goes away.

Hope Sugar perks up soon.