Except in certain circumstances there is no mal-practice in the military services for most medical treatment. If he went to sick call he more than likely didn't see an M.D. Probably a P.A. or Medic (Corpsman). The service will either keep him in until his condition is resolved and then retained or medicaly discharged or retired. He will have free medical care for the rest of his life for any service related disability.
The military is a dangerous job and even in peace time and in training service members get injured or worse die. It does not justify anything, it just comes with the job.
Look in the classified's of Army Times, Air Force Times, Navy Times or Marine Corps Times for attornies who specialize in claims against the military. Also see, the companion to this web site called Military Law at Free Advice...
Good luck.