Some questions. Has your son had any dental work prior to his inflammation? Amalgams? Root canals? What other exposures? Vaccinations? Flu shots? Etc.?
All disease is due to toxicity and lack of nutrition at all levels (physical, emotional, mental, and spiritual).
Also, I intuit that this person has closed down because he may not be following his life purpose and feels that his world has been imposed on him. I feel it is imperative that he follow his true passion.
Also family dynamics can be very influencial in these kind of brain crisis. I recommend you look into Hellinger therapy as well as Feldenkrais. Also homeopathy can help stimulate him in the right direction. Both classical homeopathy (spiritual stimulation) and regular homeopathy (physical stimulation).
At the physical level he needs to reduce his toxic total load which will allow physical healing to begin. This is acheived thru a non toxic diet such as raw vegan, removal of all toxins through avoidance and detoxification, and reduced stress by being totally inline with ones inner voice (soul purpose).
What is your son's passion? What is his current diet like?