Hi. Can anyone help me diagnose a problem in one of my chickens. She is very red under her belly and legs and has lost her feathers. At first I thought it was just moulting but it's gone on far too long now. They've been wormed and there bed checked for mites.I have 3 birds and the red one is the main problem although the black one also has a little red patch on her leg. Any help would be much appreciated.