Get the Epsom salts that is meant to be consumed, no lavender scent. It's a mild laxative.
Chickens I have administered this flush to have been energized by it. There's a good chance that she will poop, opening up her digestive tract, and she will then be motivated to drink water on her own. So assume this and don't tube plain water unless it appears she isn't going to drink.
Have you offered her regular solid chicken feed? If not, do so. The flush should open up the digestive tract and she should then be eager to eat regular feed. She can have both food and water in between flushes. But if she does eat food, wait until the crop empties before administering the flush solution.
