I've noticed lately that one of my hen's feathers are looking strange (just a patch on her back)...at first I thought maybe molting but they haven't changed in a while and she didn't lose many other feathers or anything. Also today as she was walking around the yard I noticed a bunch of white, crusty, 'stuff' around her bottom. I took pictures to give you a better idea. Any ideas or suggestions as to what might be going on with her? Should I be worried? Thanks in advance!!