I need a power of attorney document for my special needs adult son

Your son may have capacity to sign a Medical Power of Attorney appointing you his agent to speak for him when he is unable to communicate and a HIPAA Medical Information Release Authorization allowing you to access his records but he may also, between episodes, want to sign a Declaration for Mental Health Treatment stating what he does and does not want and directing people to contact you and perhaps other family members and his regular physician(s) if he is again hosipitalized.  When he lacks the legal capacity to sign these, you may need to apply for guardianship.  However, in part because people with a mental illness may present better at the hearing than when the application for guardianship is filed, it can be very difficult to protect someone with a mental illness by putting them under guardianship.