I have had a few chickens get sick and die after molting. What would cause this? I have one that is walking really slow and doesn't run from us anymore. She eats and drinks plenty of water. Help!
It might not have been molting. You might want to take one of the dead ones to your vet and see if they can determine what killed it.
You could also have sent a dead one in to your extension office for low-cost testing (it used to be free, but was a victim of one of the many cuts the govt has made recently). If another passes, you would refrigerate it, then ship it off to them for a necropsy (autopsy for non-human animals). To find where a necropsy is available in your state, start by clicking on your state in this link and contacting your state vet's office. Often a necropsy is available through a state University Extension office, an Agricultural Extension office, or a state university that teaches veterinary science. http://agr.wa.gov/FoodAnimal/AnimalHealth/statevets.aspx
I'm sorry to hear about your losses. How is your hen that is not feeling well? Can you post some photos of her? How old is she? How long ago did you hen molt? You mention that she is walking really slow - when is the last time she laid an egg? Have you felt of her abdomen between the legs below the vent to see if there is any swelling/bloat of fluid? Photos of her poop? Hopefully with some photos and more information, we can help you with the hen that is currently not well.