Have you got any Rescue Remedy (Bach Remedies)? You can get it in spray form at the health food store and some grocery chains (at least here in Canada). Put some in his water, perhaps it will help. In moments of crisis, spray directly onto his tongue. It is completely natural.
I hope your poor mother wasn't too inconvenienced
Could something have happened while he was alone in the house? Have you invited new people in, any small children who may have tormented him?