Mine are all heavily molting right now, so I do get one or two that keep their distance from the flock, get a bit skinny. Sometimes they won't even take a treat from me. In chicken biology, most (most) chicken bodies will send the protection to the brain, lungs, and heart. The last on the list is feathers and eggs , and possibly energy. Make sure she has food in her crop during the day, and is empty in the morning. If not, message their crop several times a day , (like molding clay) and wet easy digested food.
I do like natural treatments for prevention, such as greens, yogurt, probiotics, vitamins. But when it comes to my girls being sick I will rely on any medicine (antibiotics) because chances are better but not guaranteed that my girls have the best chance not to die.
I don't really believe in Epsom salts for anything but wounds because it's a salt, the rule of osmosis will always mean salty fluid will pull water out of the tissues. I've seen DE help prevent with bugs but not kill worms. DE only helps when it's dry. I don't use Oxine because from the manufacturer's label, it's "Oxine" only when activated. It does next to nothing by itself. All this information may be uneccesary but I like to give as much information as possible . I love my girls.