Dude,
I lost one of armatus 3 days ago. The feeders passed on a strain of pos bacteria, all 3 of them had bad ich and the skin was showing a signs of fungus.
Because I didn't want the smaller one to get pick on (since he look worst out of all 3), I moved him to another tank, AS SOON AS I MOVED him, he started swimming with his head up and tail down. The next day he died.
HAD I not moved him, he'd propably still alive today. The other 2 got better just by higher temp, salt and water changes in 2 days
Moral of the story, don't move him, unless you have a tankmate that pick on him. If you need to, just put an eggcrate as a divider. Don't add anymore stress to him.
I'd do a water change and salt the tank as well as add some powerhead. Turn the lights off and hope for the best.
I really hope he makes it. I like that guy
Stan