[cypher]

At 22 months it's highly likely that his kidney's aren't working as well as they would when he was younger, aside from drinking & peeing more than usual this can have some side effects which may cause slightly odd behaviour but not normally discomfort or pain so I would just keep an eye on him & let him do his own thing, there's not much you can do about it but it's probably not something you need worry about unless he shows any other more worrying signs.