Cocci keeps coming back. The flock is devastating.

[clucknpeck]

After quarantineing a new chicken for a month I introduced her to my flock about 2 months ago. She seemed very healthy. Shortly after though I lost my youngest pullet to cocci. I treated the flock and all seemed well for about a month. Then I started seeing the droopy wings again so the flock was treated again. They were all well and happy but after introducing new chicks all the chicks died. I treated the flock again.
Every time I treat them I rake and hose out the run and replace the bedding in the coop. There is 23 chickens, and 5 ducks, (all from a hatchery,) in a 600 sq ft run. Today I found another dead and one near death. I picked up all my chickens one by one and they are fat and healthy, except for a couple younger ones which aren't skin and bones, but could be fatter.
Right now my husband is finishing fencing off half an acre so my chickens can be switched to free range safely. We are hoping this will help. They get flock raiser, fresh garden veggies, and clean water every day. We are heart broken over the flock being unhealthy. They are about 25 weeks and none are laying eggs yet. We have been considering killing off the flock and starting from scratch. Can you even eat chickens with cocci??
Any advice would be greatly appreciated.

 

[Buffygirl]

Are you absolutely positive it is coccidiosis?
Have you done a necropsy?

A good way to confirm if it is cocci is to collect some poo and look at it under a microscope. If you see cocci eggs(called oocysts) you know the problem. The oocysts will look round.

I have my trusty Chicken Health Handbook sitting next to me, and it is a great resource!