Thanks for the concern, guys! I had forgotten yesterday was a holiday, so today would have been the first day I was able to call the vet. But for the past two days, he hasn't been messing with his ear at all, and he has let me touch it without complaint. He's back to his normal self, all litter box activity seems normal. I haven't called the vet, because if I can avoid the vet bill, I would like to, especially if it's going to be $100 to tell me he's perfectly fine.
I'll keep an eye on him, but I think he's fine! Although somehow, he's been gaining weight again, which I don't understand. Ah well, if it's not one thing, it's another with this cat haha.