lalaland, it could be Mareks. He is at the correct age... it strikes fairly young. It's not hereditary.
There is a cure... now lets see if I can remember what it is.
St. Johns Wort. The tiny little pills (about 1/8" diameter) in a small blue vial that you can find at a health food store. You don't ever touch the pill. The cap on the blue vial is a dispenser of sorts, you turn it and it will allow one pill into the cap, turn it again to close the slot, then remove the cap with the pill in it. You let that pill soak til its disintegrated in a teaspoon of water that you have ready and waiting for it. Once it has disintegrated, you take an eye dropper and suck up some of the fluid. With somebody helping you, you drip 5 or drips into the crack on the roof of his mouth. That's it. The person holding him should have him secured and then open his beak and tip his head way back so that the roof of his mouth is facing completely up. If you have no one to help, wrapping him up firmly in a large towel with his legs out behind him so he cannot struggle is the only way to do it. Hopefully he won't struggle. Make sure he's calm before attempting the drops so they don't get spilled/wasted.
They say to do this once per day but I did it twice per day and my bird showed dramatic improvement in only a few days. I would continue the treatment though for a week after he is back on his feet but only once per day at this point.
Hope you can get all the items he needs and that he makes a speedy recovery.