Son wants to join army, but had childhood psych hospitalization?

My 18 year old son wants to enlist in the army. He went through a very difficult time at the age of 11-12 and was hospitalized for 2 weeks for a psych eval. He was tried on several medications, and then put in a 45 day residential treatment facility. When he came home, he did better, and within 8 months was off the medications and back to his old self. He has been successful all the way through middle school and high school and has needed no further intervention. His recruiter encouraged him just not to mention it at all, but he wants to be honest. His current MD has written him a letter stating that he has not been on any medications in over three years and that he is fit to serve. We are concerned that the rules state that hospitalization or admission to a residential treatment program are a bar to enlistment. Any thoughts?