You could try giving him a bath every couple of days and see if that helps. You could add a few drops of Apple Cider Vinegar to the water. That's so lovely to hear that you are intending to let his wings grow out. It probably won't be until next year now. Has he got toys that he can chew, instead of himself? Toys tied to the side of the cage rather than the top are often easier to chew as they don't move around so much. If he doesn't play, start off with easy to destroy stuff like soft balsa wood and cardboard pieces. You can easily string them on pieces of paper rope or leather strips together with wooden beads etc.