You know my one silkie chicken wasn't acting right and I thought she was sick. Now, after all my stress and worrying, I believe she was just "broody". I didn't really know that they'd go without food and drink for so long. This is what I've been doing:
In the morning, I greet all the chickens and she's usually up in her nest box. I then put the food and fresh water in and a treat and then scoop her out of her box and place her right there with the other chickens while they are eating. I have coaxed her to eat and drink at times. I've even held her up next to the water and told her to drink.
Everyday, she'd take a little food or water and go directly back up to the nest box.
I've been doing this for a while. She appeared to be losing weight and was lighter when I picked her up.
After weeks of this, one morning, she was up with the other chickens and alert when I came down to greet them. She has been eating and drinking ever since and I think she is okay now. She is up every morning when I go down now.
I didn't do anything special, just made sure she kept drinking and had a little food.
If an egg was under her (from another chicken....since they felt sorry for her) I'd just take the egg away. She pecked at me a few times, but I still took it.