What Is The Cause For Headaches And Numbness In Hands,dizziness And Slurred Speech With Normal Cat Scan Reports?

Hello Dr, My son is 8 years old, extremely healthy to this point, academically advanced and athletic - until about a year ago when he began experiencing headaches and numbness in hands, feet and the side of his face. He now gets very dizzy, slurred speech and vision changes in one eye when the headaches are bad, as well as pain in his neck. His cat scan shows no abnormalities but he is steadily declining in health due to these symptoms. He never missed one day of school for 2 years and now he can only complete half days of school - so far the diagnosis has not been convincingly provided...can you help? Give me some sort of idea which direction I should look...we are on a lengthy wait list to see a neurologist... (over 6 months)