What was the cause of her sudden partial deafness that started a week ago? What more can be done to help?

This curious onset is the clue in understanding what happened here. It was sudden, and that is because there was an episode where she was subjected to an extraterrestrial energetic attack and it left damage in its wake in the auditory system. This we are working to heal, so time will tell to what extent this can be undone, but it is part of the ongoing effort you have launched.