That looks like what happen to my chicken back in April
I ended up having to have her put to sleep.
Egg yolk peritonitis (the presence of yolk material in the coelomic cavity) is a common cause of abdominal distension in birds.
Here is the post:https://www.backyardchickens.com/threads/egg-bound-chicken-help.1303641/

Egg yolk peritonitis (the presence of yolk material in the coelomic cavity) is a common cause of abdominal distension in birds.
Here is the post:https://www.backyardchickens.com/threads/egg-bound-chicken-help.1303641/