I'm sorry she is not doing well.
Is her balance any better?
I'm not sure about the swelling feet, to me it does not look like gout, but maybe fluid retention(?) Hopefully others will have a better idea.
With her age, all of her symptoms could be age related. Do a routine check of her - making sure the crop is emptying overnight, check for external parasites-look in the ears too, feel the abdomen for any bloat or swelling and consider having a fecal float to rule out worms.
Do what you can to keep her hydrated - poultry vitamins may perk her up a little.
I wish I had more ideas - soaking the feet and applying the vaseline won't hurt her, if she seemed to enjoy it or that helps, then do that a couple of times a week.
Let us know how she is.