head twtiches

My 17 year old boyfreind has for the past 5 years had twitches in his head. He closes his eyes, sometimes makes humming noises and isn't able to read or do anything. They happen fast but can come consistenly or just a few. He has been to the docotor numerous times and been to a neurologist along with a couple MRIs the have found nothing. They jsut assumed it was stress realted but even now that most of his stress is gone they are becomeing significantly worse.  He used to get them when eating and writting but now they are all the time. It is inhibataing his life. He is bright person and is not able to concentrate. I feel bad for him he is extremly fursterated and I just want something to help him. Please if you have any help or know someone that can help he needs it. I have never seen a young man cry from fursteration.