Hello. I have (7) backyard chickens; I did have (8). I recently had to put a chicken down, that has been showing signs of distress/illness, since last November. I took her to an Aviary Certified Vet that said she sees at least (1) chicken per week, although she also admitted to schooling herself on chickens, using the internet. She conducted a fecal float test on my chicken, approximately 3 weeks ago & only saw trace amounts of Coccidiosis, which she said is typically found in a fecal test on any backyard chicken that is free roaming. Our chickens have a yard/run that is enclosed & a nesting area, however we let them out every afternoon, for approximately 2-3 hours or until they are ready to go back in; they usually tell us, by running up to us & then walking to the coop with us. From the beginning... The two affected chickens are Plymouth Barred Rocks. None of the other chickens are showing signs. As of last November, my (1) Barred Rock starting losing feathers on her back, but it also started happening at a time when I thought the chickens were molting, as the yard/run was full of loose feathers & not all of the chickens were laying eggs. We live in FL & the temperatures were still warm with some cold days, fluctuating every other week!! As December rolled around, I noticed that she was losing more & more on her back & was concerned that she might have mights. I looked all around & could not find anything on her & when I looked at her vent, it was a little messy, with white, but didn't resemble any of the pictures that show mite or flea eggs, etc. Still I gave her a bath & blew her feathers dry. I also cleaned out the nesting area/coop, which I clean every 1 or 1 1/2 weeks, only this time, I scrubbed all of the perches, nesting boxes, flooring, walls, etc. down with hydrated lyme. I read that hydrated lyme works as an antibacterial or antiseptic & would help brighten the coop, in an effort to exterminate any microscopic bugs/mites that we might not be seeing. I then put new coastal hay down on the floor & in the nesting boxes, as I do every time I clean the coop. I also scrape the perches, etc., every morning, to clean off any poop from the night before. The sick barred rock had started sleeping away from the other chickens and sometimes on the floor, when I began to see diarrhea. I would clean it every day & then gave her a bath to help clean her vent. When I gave her a bath, many of her feathers fell off of the area around her vent, as soon as she hit the water. After she was clean, I went on here & saw a recommendation on another thread, to feed her medicated mash. I did this, by mixing the medicated mash with an electrolyte made for chickens & adding mashed probiotics; I administered this mix, with a syringe. I did this for a week or so & she seemed to be doing better, so I stopped & watched to make sure she was drinking water & eating feed. I observed her eating layer pellets & scratch, as well as drinking water. She did better for about a week & then I started noticing she had green diarrhea. I went to our feed store & it was recommended that I treat the entire flock for worms, using Wazine. I gave the 1st dose in January & the 2nd dose in February. She did not improve. She eventually started to blow "air" with not water or poop, so I went to the feed store to see what else I could do & the owner referred me to the Aviary Certified vet. $137 later, the vet could not diagnose what was wrong with her, only that she was severely dehydrated & had last much of her "meat" on her bones. She wanted me to spend up to $400 to treat her & still said there was a very good chance she wouldn't make it. I let her give her a couple of treatments to hydrate her & then when she showed no signs of improvement, we opted to have her euthanized. The vet recommended that I give my entire flock a medicated feed, to treat it for coccidiosis. I did this for 2 weeks & using a 25lb. bag of feed. After the 2 weeks, I put the flock back on layer feed & I am adding 2tbsp of apple cider vinegar to the waterer (I have been doing this since I administered the medicated feed). We are throwing the eggs out for 1 mo. post-medicated feed. The vet told me not to give the chickens an antibiotic, as we would never be able to eat their eggs again, but if we give the medicated feed, we can eat the eggs 1 mo. afterwards, b/c it will pass through their system & not be absorbed into the eggs. The 2nd chicken was doing well on the medicated crumbles, but since I have stopped giving them to the flock, she has started showing signs of a messy vent, again. She also continues to have feather loss, while not as sever, on her back. The vet did check my other chicken & said her feather loss may have been initially due to mites, but it had been remedied. She also said other than the medicated crumbles, she could not recommend anything else, other than what I have already done. I don't want to lose another chicken & I don't want any of my other chickens to become infected. The poop all looks "normal", at this time. Can you please help??? **Our chickens would rummage through our compost, but we have since enclosed the compost, so they can't get to it, in case there is something that is decomposing & has given them some sort of parasite that is not responding to the above treatments &/or detectable through the fecal float test. *TOP (3) PICS ARE OF CURRENT CHICKEN. *BOTTOM (3) PICS ARE OF CHICKEN WE HAD TO HAVE EUTHANIZED, AFTER 4 MONTHS OF TRYING TO HEAL HER.