Not exactly sure what you mean, try using more detail.
I assume you mean she/he is having watery poo, not eating, and you think she/he's gonna die.
Send pictures of the bird.
Do you notice anything else? For instance, walking funny, sitting down more, not walking out of the coop with the rest of the group? Not the best when it comes to medical problems, but I'm sure explaining more would help.
She had green foamy poo. Stopped eating and drinking. Won't move from same spot in sick pen. And now is dead. I have 2 others having treatment for a respiratory infection Bit she had no respiratory signs