Misdiagnosis

My husband is trying to join the army, and some stupid doctor diagnosed him with autism without his knowledge or his parents. He definitely does not have autism and wants to get a second opinion. With a second opinion, would he still be able to join. We have worked hard trying to get school and medical records and getting him into shape. We are desperate for him to get in so our family can get out of a bad situation. That doctor has ruined this career path for him if they won't accept a second opinion.