It does look like an onion bulb, maybe garlic or some type of flower/plant bulb. Looks like there's evidence of root and the green is beginnings of the bulb sprouting.
Definitely not Lash Egg.
She's drinking a lot of water. Address that symptom. Begin treating as sour crop. Get coconut oil into her and start a yeast or fungal medication. Here's an article that will help.
https://www.backyardchickens.com/ar...w-to-know-which-one-youre-dealing-with.73607/
Do you have a compost or throw out compost/kitchen scraps?
Do you provide Grit (Crushed Granite) for the birds free choice?
The poop doesn't look very good. I'd consider deworming. Valbazen as suggested is a good choice.
Hard to say what's exactly going on with her, but those 2 things you can address. Could be there's an underlying condition that is at play and you will not discover that unless she doesn't make it and you either send the body for necropsy or investigate yourself.