Many ekkies become sensitive to protein (beans,nuts, etc), animal protein (eggs, chicken), vitamins in pellets, spirulina in pellets and prepared foods, added vitamins, sugars, preservatives.
Regular soaking baths or showers are a necessity. Dry, itchy skin can cause scratching and over preening. The fine ekkie hairs on the head and chest can be ripped out by too exuberant scratching.
If you blow dry Howard do not over dry but allow him to air dry if possible. Also use dryer on cool or lowest setting and do not hold the dryer too close to his feathers.