I had a similar problem with my flock. We have to much rain and couldn't mow yard, where chickens at and grass/weeds got high. I noticed one lethargic hen and gave her 4 dropper full of pedialyte with sugar in it and multivitamin for chickens and 4-5 vitamin e capsules in it. Put her back and she got better, then 2 days later another lethargic hen in worse shape. She dropped her beak to the bottom of the hospital cage i had her in. I really had to work hard to get 4 dropper fulls in her. Next day, she was well. Both hens had diarrhea.
Then, I noticed little nats all around in my yard, red nats. All of my chickens had flying tiny bugs all over their butts. My head was itching after caring for them. So, the rain stopped awhile, I mowed, dusted the birds, put lime around coop and run, kept the poop pdz'd, put tea tree on my scalp before going out, diluted tea tree with water and sprayed all their butts (only prevents bugs wont kill them), sprinkled baggie of lavender buds, thyme, cloves, and sage all over in coop and run (wow did this smell good and still does). I kept yard mowed in between runs, and poop dried with pdz, and you could still see bugs on their butts and in my yard everywhere!
Someone recommended that I get Adams dog flea and tick spray and spray them with that. I did that and couldn't see the bugs 2 days later, so I just sprayed again after the 7 day period was up, over the weekend and thank goodness, no more bugs flying everywhere. It cost me 20.00, but it was worth it! I plan on spraying there butts, lightly every 7 - 14 days through the rainy summer.
