Chickens are survivors, they aren't gonna die because they don't like the food. They will eat almost any thing and they would only not eat if they couldn't eat what was available. There could be a crushed egg, what is her poop like? White and liquid like? Feel her abdomen between her legs, What does it feel like? Large, squishy?They aren't due to lay for a while. I also double-checked for a stuck egg and there wasn't one just now. She isn't laying yet though so I didn't really expect there to be one. But why would she all of a sudden pretend like nothing was wrong and start eating the old food after not eating for a few days? She pointedly walked around the new food to get to her private cup. I know that some of my birds prefer certain treats over others, so that's why I think being picky could be possible.