I have 2 year old Plymouth barred Rocks one is I think near death. She has been ill for 2-3 weeks. Lethargic loosing weight and has a nasty comb see photo. The others are fine except one has small black spots on her comb. Treated the water with a probiotic and have been tilting the sick hen upside down to drain her crop of fluid. At one point she seemed to be recovered but now is back to hiding and tail down. Thoughts ??