Silkie Rooster not walking and shaking like a leaf.

[Rainbowfamily]

My little Silkie Rooster Maleficent the magnificent is very ill. He seemed ok yesterday, a little off but it has been bad weather and they are in the coop or the shed for the last few days, so not too happy. I went out to do the rounds this morning and he was off in the darkest corner by himself unsteady on his feet, wouldn't eat his favorite treats. I went over and picked him up, his feet curled in under the towel I brought. I got the muck off, he is molting so he doesn't look great right now in general. His eyes are fine, doesn't seem to have respiratory issues at this time. I checked him over for other injuries and didn't see any. About two weeks or so ago he was de-throned from top cock by his son. But again doesn't seem to have any injuries and was fine for all this time.
I have separated him from the flock, given rooster booster in the water in their along with his favorite treat mix. He hasn't moved out of the towel he is wrapped in. Any suggestions as to what the illness may be?

 

[ChickNanny13]

Picture would help ... You say he was "dethroned", has he been eating/drinking/pooping? Check his crop, see if it's empty (AM) or full (PM). Was he wet? If so dry him off with a blow dryer, make sure he's not chilled. Good that you separated him, give him time so settle in & easier for observation. Rooster Booster is good but would you have Nutri Drench? It absorbs into the system "faster". You may want to scramble up some eggs to see if he'll eat that or some tuna, you can also wet his feed to make a mash to try entice him to eat.