Have you tried making him sleep/hang out in the bathroom, with the shower running? My guys love the humidity each morning. I also don't keep my house very hot... in an effort to keep the air from drying out too much. I have humidifers but don't have to use them that often. They can add insult to injury if you don't maintain them properly and will breed molds etc.

Hope your xray process goes ok. They will probably knock the cat out for it.

Fingers crossed for a correct answer for you and your kitty.