I agree that there may be some sensory over-sensitivity going on, whether it's visual,auditory etc..can be determined by an accurate funtional analysis. Massage therapy may help your son or it may not. That in itself will most likely not give you the function of the behavior. How does your son communicate? I have had student's who have banged their heads in an attempt to relieve a head ache because they couldn't communicate the need for relief to us. Anyway, I would recommend first a functional behavioral analysis so that a behavior support plan can be implement to spcifically address this behavior. It's without question, to the point where it's now a medical/safety issue that could lead to traumatic brain injury.