When we first had Isolde of the White Paws, Jon insisted on playing 'bed mice' with her by sticking his toes under any piece of newspaper or cushion that happened to be handy. She now has a foot fettish about his toes and he has to make sure she isn't around when he steps out of the shower or she'll try and lick his toes to death!! I did warn him but would he listen???? She did have a hair loss problem a few weeks ago but that is now growing back or I'd have to make her a tunmmy warmer for the winter. She had found a hedgehog in the garden and picked up fleas from it, which, according to the vet, are more virilent than ordinary cat fleas. She had never had anything like that before and went wild trying to pull her hair out. See if he's been in contact with any other type of wildlife that she may have picked something up from. It does sound, though that it is a recurring problem and it may be that he has had a cahnge of routine that has upset him or is feeling lonely. You could adopt a friend for him... another young cat looking for a good home or even an older female cat who might mother him.