Is he by any chance beginning a molt? Molting takes a lot out of a bird and they can become less energetic and crabby. Any sudden change in behavior should be monitored closely, birds are masters at hiding illness and once we see outward symptoms they could have been ill for a while. Could he be stressed out by the cats? Do you keep him in an area where the cats are never allowed or can the bird see the cats? Since birds are prey animals and cats are predators even the sight of a cat can cause stress for the bird which can lead to behavior changes.