I think you should ask your Dr.'s what they think about neurofeedback before you try to provide it for your son.
In my opinion, it could cause more damage than good. It's not an exact science and I believe the practitioners may believe that they are helping patients but they are truthfully just profiting off the fears and desperation of people who have suffered tbi's who are impatient to get better faster or who feel like all hope is lost.
He is so young, neurofeedback makes me nervous for an adult - but for a child it downright scares me!
I think it should be reserved for a last ditch effort and you still have lots of avenues to try before trying that.
It sounds like your Dr.'s are doing everything that they can - especially if his next step is heading to a neurological headache institute. That sounds like a great thing where experts with the most up to date research will be able to help your son.
I know from personal experience that it's very difficult to be in severe pain and wait for a concussion to "get better" in it's own time and I can't imagine what it must be like for a mother to watch her son go through excruciating pain, but hang in there, because it sounds like he's in good hands and that the situation is being taken seriously.
Has anyone really taken a look at his neck? Has he been given any MRI's of his neck? Has a neurosurgeon taken a look at them?
Many neck injuries are being proven to cause PCS symptoms including headaches.
Our necks try their best to help protect our skulls when they are traumatized, but often our necks aren't strong enough to do so and they can become injured themselves in the process.
I think it's worth asking for in addition to going to this institute they are sending him to.
He may not need any surgery, but only some physical therapy to get him on the right track to wellness.
Doing a quick google search for "Ann Arbor Concussion Specialist" I found that the University of Michigan has a Sports Concussion Speciality Department... have you contacted anyone over there for a referral for a pediatrics specialist for concussion? They may be a good resource for you to touch base with for a referral.
Before going with a random "practitioner" who performs neurofeedback, I would seek out researchers and experts in the field who are bonafide MD's and PHD's with experience treating children recovering from concussions.
I also found a concussion clinic in the detroit area:
http://www.henryford.com/body.cfm?id=40876
I'm glad you have tried so many things! I did the same when trying to recover from the concussion I sustained too before I figured out what worked for me.
You are clearly very motivated and resourceful, just hang in there and it'll work out. (((hug)))
I think he should continue to take the supplements until he's much better and maybe for the rest of his life anyway... they will help in an ongoing capacity that may not be apparently detectable.