The buff orp in my avatar passed from internal laying and/or EYP, and her poop looked liked scrambled eggs. She was also not moving much and was puffed up as you described. Have you felt her abdomen? Does it feel swollen? Even if you are lucky enough to have a vet that will see her it may only be a temporary fix. I am so sorry. Hopefully I am wrong.
Oh so sad to read how old ur hen was