When might it be necessary for you to pass on confidental information?

The only reason that you would need to pass on confidential doctor-patient information is when your patient is in danger. If they are going to hurt or kill themselves, or someone has threatened them or hurt them in any way, then you are required to get them help, and the only way to do that is to tell someone. It is completely ethical and moral for you to share confidential information in this situation.