If it's gout, you may want to have your vet check the uric acid levels. Sometimes a chicken will get gout because it only eats seeds/pellets. I had read this somewhere a while back.
I've had a hard time finding a vet that would look at Chickens. Give them a dog/cat and they're OK. They just chuckle when I mention a chicken!
Are you using hydrated lime in your coop somewhere?
No, the only thing I use is DE.
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