The swelling may be from the mites and her having a hard time getting around.Thank you so much for your information. So the swelling is because of the mites? Or does that need a separate treatment? thanks
You can give her legs/feet a soaking in a warm epsom salts bath a few times a week to see if that helps reduce swelling.
Hopefully the swelling will start to resolve as the mites and nails are taken care of. Gout is a possibility, but I would treat the mites, trim the nails and give her some foot soaks. See what happens.