Her crop is full during the day, but is it
empty first thing in the morning before she's had anything to eat/drink?
Obsessed with drinking water, usually this is a digestive/crop issue, but there could be something else going on. What do you feed including treats? How old is she? Does she lay eggs, what are they like?
A photo of her overnight droppings?
Re-check that crop to see if it's emptying.
Look her over for lice/mites - look around the vent, tail, wings, etc. all the way to the skin, move the feathers around and look really well.
If you feel she may benefit from deworming, then use an anthelmintic. DE is not a dewormer so she will not benefit from your giving that to her. Yogurt in very small amounts can be given, but it needs to be a quality plain yogurt, but it's not that effective in treating sour crop.
You can find Safeguard 10% liquid goat dewormer at most feed stores. Dose is 0.23ml per pound of weight given orally once a day for 5 days in a row.
Alternatively, you can use Valbazen (
order it online) dose is 0.08ml per pound of weight given orally once, then repeat in 10 days.
If the crop is not emptying, read this article and follow the treatment protocols.
https://www.backyardchickens.com/ar...w-to-know-which-one-youre-dealing-with.73607/