@tjs22 it's good that you were able to get some water into him.
Photos will be most helpful. I agree with
@oldhenlikesdogs if he was pecked or beaten up, this could be the cause of his symptoms. Injuries can make a chicken lethargic, so more information is welcomed.
Hi
@Sinful chick I'm sorry to hear your rooster was attacked. If you prefer, you can start your own thread - you will get more answers, but we will be glad to help you the best we can.
It sounds like he has extensive injuries to the neck, is that correct? Are his wounds healing - do you see any signs of infection?
It good that you are able to get food/water into him - add some poultry vitamins to the water or direct dose him once a day with Poultry Nutri-Drench at 1cc per 3lbs of weight.
Keep trying to get his normal feed into him, some will readily eat a little egg on their own, so you might want to see if he will take that as a treat - but he does need a balanced poultry feed if at all possible.
Is he unable to stand? You could try making him a sling - this may help strengthen the legs - google "chicken sling" and you will find a lot of creative ideas.
Hope he gets better soon, please keep us posted.