Unfortunately, yes, I have seen this. The may be a couple of things. One of the worst things it could be is internal laying or lower abdomen filling with fluid, ascites, that kind of thing. Keep a watch on her.
I think you are onto something! Her abdomen is huge and hard as a rock. It is getting bigger and her legs are growing wider. Is there anything I can do? She eats and drinks and acts normal, except the limits on her mobility. Even so she gets up and down my porch steps and walks around in the yard. Her breathing is a little fast and hard. Of course she can't perch. At the very beginning when her legs were maybe only an inch too wide, the other chickens tried to kill her. That is why she lives on my back porch. She is very content. I let her out in the morning and she comes up at dusk to be let in. She has been living like this for months. It's quite adorable, but I would rather have her healthy. Thank you for taking time to respond. I really appreciate it.