I'm not sure what's going on. She sits in one place with head hanging down. Looks like she swelled up with fluid also. Her comb is hanging down with dark ends.
Loos like fluid upper and lower. When she stands up you can see it. This profile shot shows the lower.
i'm in big city. Mr Possum and Mr Racoon only come by once every few years or so. My two hens are caged in and sleep in their coop at night.
It looks like she could possibly have Peritonitis or Ascites. The fluids building up in her most likely will cause or have caused an infection and ultimately heart failure. Sometimes an antibiotic like Baytril or enrofloxacin (shouldn't be used in birds used for meat) can help relieve some of her discomfort from infection. Some people drain the fluid from the abdomen to give supportive care.
I have never seen the swelling at the "top" or on the back of the chicken before though, wandering if some of her air sacs are fluid filled also. You can get antibiotics are the feed store, they may help, but a lot of times it is going to be for supportive care.