Thank you so much for the vibes, everyone.
Omi, I haven't found a store here that sells Readigrass, but I have some stuff that's basically the same as far as I can tell, but from a different brand. He eats some of it, but he doesn't love it, sadly.
The vet appointment went okay. I got the impression that the vet was a bit annoyed with me for asking them to check Casper again.
He couldn't find anything in Casper's mouth and was sure his problems eating hay are because of his tooth roots hurting him. He said it's not that bad if Casper won't eat hay and that I can just give him lots of greens instead, as long as they're low in sugar and high in fibre, and that the important thing is that he eats something, and it doesn't really matter whether that's hay or something else. He said that hay is such a popular thing to feed rabbits because you can get big bag for very little money (I guess he has never seen the amount of money I've spent on hay...), but that it's not actually better for them than other food (which kind of goes against everything I've ever read about bunny diets? But I'm not a vet), and so it's fine if he doesn't eat any. So, I'll see what kind of greens are high in fibre...
Casper's poops were pretty small today, and the vet checked his belly and said there wasn't enough movement, so he has Emeprid and Ciseral (good call, bunny momma), and the vet said to raise his Metacam dosage and see if that makes a difference. The meds might encourage him to start eating hay again, but the vet seemed to think it's very likely that this will just be the new normal for Casper, and that his dental disease has just progressed too far for him to comfortably eat hay anymore. He also mentioned several times that his dental disease is most likely what will end Casper's life, but that it's impossible to say if that'll be next year or next week. That's not news to me, but the vet could've been a bit more gentle about it...