hello thanks for posting in HCM I have understand your concern with the history given by you I m thinking that you may have injury to vertebral bone or disk that is compressing nerve roots and giving pain in arms responding to steroids because there may be reactionary edema and that resolves with Prednisone breathing difficulty may be secondary to muscle stiffness secondary to pain I can suggest you to get done x-ray cervical and thoracic spine AP and Lateral view. mean while continue with the medications you are on.