one of my hens has lost the feathers on her bottom, and when I touch it, her bottom area seems swollen, as if it's filled with fluid. Strange. She's about a year old. She seems otherwise healthy, eats. She had some poop stuck there a few days ago, I soaked her in warm water and washed her off. Did it again today, which is why she is wet in this photo. I do not know if she's laying, as I have a few hens. Apologies for the uncleanliness of the photo. Any advice would be gratefully accepted.