Smokey is feeling much better now. He wouldn't eat at all so we resorted to syringe-feeding for a few days. He was relatively (and mercifully) cooperative. The vet did several tests and nothing out of the ordinary was found, so the current hypothesis is that one of, or the combination of his medications was making him feel sick and nauseous.
So the plan is to take him off the meds for a short period, and then gradually reintroduce them one by one.
It seems to make sense, because although syringe-feeding did *slightly* revive his appetite, his interest really started to come back a couple of days after stopping the meds. Of course, this doesn't actually prove that there's a causal relationship...the two events just followed each other in time. But I think it's a reasonable avenue to pursue.
It's tricky though, I'm starting to appreciate how difficult it must be for vets to diagnose and treat patients who can't speak! It's really like detective work.
Anyway, Smokey is eating again, although he is being very picky about what he will and won't eat. This might be a result of the way we treated him when he wouldn't eat, which was to be extremely indulgent just to get him to eat *something*. He seems like he really expects to get treats all the time, so I have to get him used to the idea of eating normally again.
His poops looking good and normal after a short bout of diarrhea.
Essentially, he's not acting sick anymore, but there does seem to be some kind of (recurring?)issue with nausea/acid/indigestion that is eluding us. Whether it's just a side effect of the kidney disease that has its up and downs, the vet's too many meds theory, or a separate gastrointestinal issue (IBD was briefly brought up but the vet hasn't spoken much about it yet), I have no idea. We're working on it though. In the meantime, I'm at least happy that his blood work is pretty stable and he's being a very good boy about his fluids.