Well, he's not getting much better as of now.
I have a scarf wrapped around the tank to create a dark atmosphere, to help him sleep, and also to prevent his reflection from showing.
I've been taking the scarf off, checking on him every few hours, and his fins are open, as if he's been seeing his reflection. It's hard to explain, but it's as if he's still seeing his reflection in the dark. He's sleeping though, but I don't like it...
I'm doing a water change today, and I hope it will work. Then I'm going to return him right back on the shelf with the scarf.