I have a chicken that has a swollen abdomen with no feathers. She always stays in the nesting box and sometimes moves to a different one to sit on the other chickens' eggs. At first I thought it was just a phase of being a mother hen, since I had another chicken that did that and is fine now. But then I saw the abdomen. It feels squishy like a water balloon. I'm very worried and I don't know what to do. Thank you for the help!