About a month and a half ago I had a black giant get ill. Off balance on her feet, slowed feed and tons of water type diarrhea. I thought everything in the book since I am fairly new to chickens. They are all over a year old and I have 19 laying hens: 3 jersey and 16 black sex-link and 1 roo 6 chicks hatched by a broody jersey too. Then I had another hen get ill with what looks like wet pox and in the last 4 days have had another jersey and black sex-link ill standing with fluffed feather huddled together with fairly empty crops at night. I treated with sulmet and they seemed better for a day or two, but not recovered. Have finished sulmet today. Also the 2 I separated from the flock have not died and have been ill for a LONG time. Dramatic drop in egg production from 16 eggs a day to less than 5 most days, but some are also molting. Then today I finally see it on one of the jersey's a red mite. So I am guessing that is what is making them ill, but also why they are not dying either. I need to know how to treat this we live in TN fairly warm with a few months of cold. Their coop is in the back of our barn in a shed. It has dirt floors and wood walls on three sides. How in the heck do I clean dirt? Do i spray the walls of the barn the nesting boxes the roost and with what? Trying to keep cost low, I am gonna use ivermectin pour on to treat mites on the birds will that be enough?