I'm having the same problem with one of mine. Someone suggested it might be peritonitis from "internal laying". Idk? Even vet couldn't figure it out. Have her in antibiotic injections for the 4th time in about 7 months.
I'm having the same issue with one of my girls. This is the 4th time in about 8 months that I have had her on antibiotic injections. She slowly gets better.... Is good for a couple months.... Then sick again. If it is peritonitis...… is there a cure other than what I'm doing?
I have 4 chickens in a rather large coop. (The coop is rated for up to 8-12 chickens!) Have had them for about a year and a half. I have noticed that 2 of the chickens have been plucking the feathers from one of their room mates! They have lots of space, good food, clean water, clean boxes...