It is recommended that you have one more litter box than cats. I would suggest getting another if not 2 more. Has Joey been dewormed yet? As for the strange behavior maybe Joey isn't feeling well and a trip to the vet is needed. better safe than sorry. If Joey is healthy then you have peace of mind knowing he is fine but if god forbid something is not quite right then you would have gotten him the help he needs to feel and get better. Keep us posted ok.

Michelle