I am not sure what is wrong, but I have one that is kind of like that. I have found feeding her high protein has helped. I know she was sick earlier.
I would try the "show bird conditioner" from fleet farm a ton of vitamins and minerals in 24% protein. It is too expensive to feed this only. I would also get a bag of 32% calf conditioner "Calf Manna" It is around $14.
I feed this with a couple tablespoons full of the conditioner. BTW this same concoction will speed up the re-feathering after a molt.