Good post Dantes, thanks. There is the chance that Mokkun isn't tolerating a multi-cat environment which could be the source of stress. Perhaps regularly giving him a place of his own to chill away from the other cats would help? If it is multi-cat stress maybe it's just one of the other cats contributing to the issue?
Good luck Sean. Hugs to you and you Mokkun.
Good luck Sean. Hugs to you and you Mokkun.