you cannot depend on docs to diagnose you accurately. they are more concerned with their golf game than their patients.. i've said this many times and its true. i know cause i play a poker home game with docs, one got called for surgery during the game and he insisted on finishing his hand while the patient was in the hospital dying. docs are scumbags, most of them that is.
a holistic doc like said above will care more about you but will still have to send you to get blood work done. you want to know what i would do? if you insist on using docs, you need to see multiple docs, not just 1.. laws of averages, i would think if you see 5 or 6 docs and get their opinions you will find a competent one.
otherwise get your own blood work done like i do. its easy and you don't have to go through any docs. sites like privatemdlabs.com .. you can see what is abnormal then use online pharmacies to order your own drugs.. i am my own doctor, all a doctor does is the same thing.. he sends out for 'tests' (most of which are a waste of money) finds whats wrong with you, then puts you on drugs. so why not cut out the middle man and do it yourself? thats what i do.
now in your son's case lets back up to the start. what is his lifestyle like? from what you write he has poor sleeping habits which can cause even more issues.. but if the underlying problem is causing the sleep problems we need to back up and solve that first. now a doc is gonna put him on sleep meds for the rest of his life and not fix the root problem, this happens in almost all cases.