Hello everyone, I am new to this site, and going into my second year of raising chickens. I have a flock of 14 golden comet girls. About a month ago, I noticed one beginning to walk very slowly and her comb became very pale. It was difficult to tell if she was laying because theres so many. I assumed she had an egg stuck (her belly was swollen), so I was doing epsom salt baths, but unfortunately she passed. Well now almost two months later, I have another girl who has a red and inflamed rear end, and noticing poop sticking to her behind feathers. I again assumed she had an egg stuck (we recently added more calcium to their diet and they free range) so I have been soaking her. She has been like this for about a week, still eating and drinking, but continues to be reddened and poop. Well now I am noticing more girls having this, and I found another dead one without any other symptoms or anything. I am wondering if there is some sort of bacterial infection? All of their poop appears normal (not frothy or diarrhea). I have added some vitamins to their water, and also apple cider vinegar. I have attached a picture of what it looks like (sorry I know it is gross). I guess my question is should I treat the whole flock? Any other suggestions/advice would be very welcome, I am very distraught about my girls!