I think just keep doing what you are doing. If you have a routine, stick to it - maybe ask if he wants to come out to hang the washing out (or whatever reason you have to leave the room) so he feels like he has a little bit of power over the way he is feeling.

I am absolutely sure he will recover, I think time is the key here. Continue the great job you are already doing

P.S - If you have any Rescue Remedy around, he would probably benefit from a few doses xoxoxo