It's mites! No joke! That's how Sunny looked at first when the mties began infesting!
Take him to the vet and they'll do a skin scraping to make sure. They'll give him either antibiotics or an injection! Poor baby!
Quarentine him! OMG. Is he with all the other birds? Maybe by some miracle, it's not mites and it didn't spread! But that's how Sun looked!