Have you checked her crop to make sure it's emptying overnight? I understand she's puffed up, but that stance I've seen before in hens that are having reproductive issues (trouble laying an egg, peritonitis, cancer, etc.) and the crop has slowed due to inflammation in the body.
I would feel for an egg, feel the abdomen between the legs under the vent for fluid or bloat. Monitor the crop to see that it's emptying, if not, then begin crop treatment (I start with giving coconut oil - it's all in the article linked below).
https://www.backyardchickens.com/ar...w-to-know-which-one-youre-dealing-with.73607/
I would feel for an egg, feel the abdomen between the legs under the vent for fluid or bloat. Monitor the crop to see that it's emptying, if not, then begin crop treatment (I start with giving coconut oil - it's all in the article linked below).
https://www.backyardchickens.com/ar...w-to-know-which-one-youre-dealing-with.73607/