Can you post some photos of her?
Feather loss can be due to lice/mites, feather picking, molting and mating.
If she has increasing baldness, someone may be plucking her feathers out or the rooster may be overmating her.
Sometimes a bird will isolate themselves when they are not feeling...
Try to limit your treats to no more than 5-10% of their daily intake. A lot depends on the protein % of what your regular feed is. Anything you feed in addition to a balanced poultry feed dilutes the daily protein/nutritional content.
Wax covered looking feathers - what you are seeing is...
It does look like molting to me, they molt at various stages sometimes and can look a mess. I think you did fine giving her a dusting.
Also take note to see if any of the other birds may be plucking out new growth, especially during roosting.
Just keep a watch on her to see that she is...
Photos will be most helpful.
How old is she?
Look at her to see if there is new growth (pin feathers) coming in. That would indicate she is molting.
If she is really naked, then you should be able to see lice moving on her if there is an infestation - look around the vent, under the wings...