As a concerned parent - your best bet is to go to the XO or CO of the recruiting district. That will get the ball rolling, at least it should.
First things first though - how long has he gone without contact from the recruiter? It may be he is on travel or leave? Shore duty typically means guys are trying to get a personal life again, and unfortunately, he may drop the ball at work. I would make sure you have 2 weeks with no contact - after that - contact the CO or XO. Once he is in the military, I wouldn't take that route - but as a concerned parent of a student is trying to get in the Navy - it is fine.
Hope that helps. I was a former NUPOC guy, I remember a lot of waiting, fortunately, my recruiter spent all his free time making sure I didn't change my mind.