Charlie update:
Ted and the specialist have looked at a couple of videos I took of Charlie during his 'episodes'. They both agree it certainly seems upper respiratory tract related, and the best thing to do at the moment is for Ted to put a scope down his throat, take a look, turn it round and look up his nose. He thinks it's possible he could have something stuck under his soft palate, and that what we're seeing is in fact reverse sneezing and other related things as he gets irritated and his reflexes kick in trying to get it out. He said it's rare-ish but he's seen another cat this week with something stuck under there. Often happens with blades of grass and other linear things like that (he's an indoor cat, so it's not grass, but he has a taste for plastic...)
An outlier is it could be polyps, which are quite rare in cats, but not unheard of. They're trickier to deal with. Ted's never seen them, and would refer me on to the specialist to deal with. From memory he said he thinks they can often grow back.
So that's what we're planning at the moment. He said one of his colleagues could do it on Friday, and they would be perfectly capable, but honestly he'd prefer to do it (I think he's super curious, but also it's good to maintain consistency), so we're looking Monday or Tuesday next week. It'll mean a GA, and if there is something under the soft palate he'll be able to remove it there and then.
The slightly higher dose of steroids, in the meantime, have had a positive effect, and Charlie's back to purring every now and again (although it sets him off) and he's tried to settle on my knee a couple of times (doesn't last long because I think he's uncomfortable) and jumped on the bed twice last night too. He's not hiccuping (or whatever it is) as often, nor for as long or as violently. He seems to be able to get rid of them really quickly now. But anything and everything will set them off.
Of course, I'll be a mess because of the GA. I'll have the usual anaesthetic complications worry, compounded with the "will his throat spasm while he's under and will he die" worries. And then there's the "what if they don't find anything, what next?" worry.
Also, on the shaved patch on his throat where they took blood when he went in and was sedated a few weeks ago there's a small lump. I mentioned it to Ted last time I went in for a checkup and he said it's likely an edema caused by taking blood, nothing to worry about, it should go in a week or two. It hasn't. If anything, it's a bit bigger, and hard. So he's going to take a look at that too. It's only about pea sized, but still. If it is a tumour of some kind, his blood results were perfect just a couple of weeks ago, so we'll have caught it early at least, before it had chance to wreak havoc on his health proper.
Trying to stay positive!