my 9 year old african grey is going bald

by kristy
(hertfordshire, united kingdom)

hi, my 9 year old african grey has lost all his feathers on his legs, from his neck starting right from under the bottom of his beak down to chest, belly (underneath) and around the back of his neck. this has all happened in a maximum of 3 days what could this be? he is still playfull, talking, eating and drinking and has never had anything like this happen before.