I have a hen that is about 2 years old. She is going bald on her head, random patches and completely red raw on her butt. She has scaly feet(parts are bloody), and I’m sure she is the culprit of the diarraha in the coop along with a egg without any shell. She is acting normal, very alert and running around like normal. I thought that she needed more Ca so I have been giving them their egg shells back but it doesn’t seem to be helping... Is this mites? She is the only one affected for about two weeks now. I can’t catch her for pictures at the moment hopefully I can get some pics up later.