I have 4 backyard year old laying hens which lay regularly and all appear to be healthy. One hen has had very watery stools for several months, and small blood spots on some of her eggs.but otherwise seems okay. Today for the first time she had a bloody stool. How should I treat this? I plan to separate her from the others for now until I find out what the problem may be. They do not run free in my backyard but have a very generous enclosure which I clean frequently. I am in the San Francisco area so live in a very mild climate.