Is a vet in another area an option?
Many different respiratory illnesses can cause squeaky coughing and head shaking, CRD is one of them, irrigating his face could indicate something obstructing his sinuses, but the most concerning thing is the loss of his honk as voice and pitch changes are more of an indication of aspergillosis.
Some lower intestinal infections can cause symptoms that imitate a lower respiratory infection because a swollen bowel can press into the lower airsacks which can cause heavy breathing and even coughing, it doesn’t cause changes to the voice but it’s something worth considering. If you’ve noticed any odd droppings like orange, yellow, salmon, red, black, excessively white, bright green, or mostly watery or bubbly that can indicate something like coccidia, giardia, clostridium, or something else that could cause that.
Unfortunately if it is asper that is something that can really only be treated by a vet and the sooner it’s treated the better chance he has of recovery. Asper is insidiously sneaky and noticeable symptoms usually only appear when it’s already spread and become life threatening.
