Well, ~if~ he sticks around, it would be good to get him in to a vet next week and get him on some kind of treatment that's appropriate. He's obviously had some kind of serious itchy problem that might be about cleared up, but sometimes it just becomes habit to lick and chew.
I'm still deciding if he's going to stay in for the night or not. We just had a minor squabble, for no apparent reason, after several hours of them being OK inside together. They're back to sleeping again, but it makes me nervous.