My rooster is suddenly ill and weak. Won't eat nor drink. Will lay and close his eyes.

I need help please. I visited the coop this morning and I found this rooster very ill, laying on the ground, doesn't want to eat nor drink. I prepared solution of vitamin water and that is what I am forcing him to drink. I don't know what to do. He is very cold. Doesn't want to eat nor drink. His eyes are closed and won't open them unless I am moving or disturbing him.