Consistent nausea, vision problems, fatique

My son was diagnosed with insignificant Chiari by a radiologist at age 16. Little did we know when we wanted someone who sees the condition regularly, the neurosurgeon at Johns Hopkins evaluated the MRI and his cerebral fluid was drastically diminished. surgery was required.  He had successful decompression surgery 3 months later...now 2 yrs have passed and in one way, he is better off. His horrific headaches have stopped and his cerebral fluid is flowing and he wont be at risk of syrinx or other cerebral pressure.
Problem: where his brain was accustomed to living with no space, there is now much space. According to his neurosurgeon, he did not need to insert a shunt and the surgery was successful. The op report indicated very thick muscle and soft tissue and he did go through the dural space. From all indications, he has a lot of scar tissue.  His migraines have switched to "abdominal type" and he bouts with nausea a lot. He has vision problems with convergence and explains that his brain feels "wound too tightly" and he then sees life in "snapshots"..ie, he sees blocks of vision when looking at things and his eyes fatigue after 15 min of reading.  His appetite is not good and in the last 2 yrs since surgery, he is 30 lb lighter.One piece to the story is that he is an athlete that excels and was advised he could go back to playing football 6 months after surgery. He did so, which likely caused his problems to become worse. He suffered another concussion before quitting for good. He is trying hyperbaric oxygen upon recommendation of a neurosurgeon (2nd opinion doctor to return to football). This doctor diagnosed his vision problems which are related to messaging between his brain and his eyes...although he has 20-40 vision. He was then referred to a behavioral optometrist who prescribed reading glasses and sees a neurologist for the other symptoms.His life has changed for the worse since diagnosis and decompression, although his cerebellum is clearly not in the cord area which means he shouldn't have to have another surgery.Any knowledge, suggestions, or input would be appreciated