Have you tried using pure aloe on him? If you mix some organic aloe juice with filtered water and spray/mist him with it, it just may help with his itchy skin. After going back and rereading the post I've noticed something that you may not be aware of. You say that you used non irritant laundry detergent and have not used any cleaning chemicals near the birds. Keep in mind the laundry detergent is made for humans. Try washing their things in white vinegar. It cleans safer than any chemical and is almost like using bleach as far killing germs. No laundry fabric softeners or sheets when you dry them. Also look at what are you using to clean the cages, rag vs paper towel vs scrub brush and what cleaner. I can't use most of the "bird" cage cleaners because they flair up my allergies with sneezing and asthma. Water works great to get rid of poop and again vinegar as a cleaning solution. I use 1 cap full in a spray bottle filled with water. When he is perched on your leg or lap is he sitting on your clothing? You may want to wash a separate towel without chemicals and keep in your lap when he's sitting with you. And your hands will transfer anything that you have been using from cleaners to lotions onto him. Sounds like a lot but it may just help you figure out what he's reacting to or if it's indeed a behavior. Best of luck hopefully it clears up on it's own soon.