Budgie swollen joins & white "pimples" on both feet

by Genevieve
(South Africa)

Two weeks ago we noticed that our budgie was unable to grip with her feet and that her feet were rigid. We then noticed that the joints had swollen and the feet remains rigid. We also noticed that there were white bubbles on both her legs. She flies well and is eating. I have tried bathing her feet in a very mild anteseptic. Can anyone advise what causes this condition and if it cureable? Is it treatable? I would appreciate your feedback. Many thanks. Genevieve