Is he having any other symptoms or doing anything else that isn't normal for him? Is he still eating and drinking the same amount, has he lost any weight, is he sleeping more than usual or acting lethargic during the day, how are his droppings, do they look normal or are they a different color or runny...
We need some more info about your bird's behavior, as just swaying a bit when he sleeps might not be anything at all, or it could be a bunch of things.
If you ever think something is wrong with your bird you should always take him straight to his avian vet, as it's usually very difficult with birds to catch illnesses early on because they hide sickness and pain instinctively. So it may be best to just get him to his avian vet ASAP. But more info about him and his behavior and habits might tell us something.
Does he sway or is he off-balance at all while he's awake? Does he ever fall off his perches or have trouble climbing his cage?
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