You are getting great advice, but I have a few more ideas.
Is it possible there is something in the run that is poisoning them? You might check plants and maybe have your soil tested.
Have you checked their crop function? Crop should be full at night and empty in the morning.
Have you wormed them? You might have a fecal float done.
There are diseases that can lay dormant in a flock until there are new stressors.
Can you share the state lab necropsy results?
I'm really sorry you are going through this... I hope we can help you find answers.

Is it possible there is something in the run that is poisoning them? You might check plants and maybe have your soil tested.
Have you checked their crop function? Crop should be full at night and empty in the morning.
Have you wormed them? You might have a fecal float done.
There are diseases that can lay dormant in a flock until there are new stressors.
Can you share the state lab necropsy results?
I'm really sorry you are going through this... I hope we can help you find answers.
