Dear Julie,
You may be putting the cart before the horse, so to speak. You are seeking forms of treatment when it may not be entirely clear what the diagnosis is (or what the diagnoses are).
I'd be wary of attributing all your son's difficulties to sensory integration disorder, though in its severe forms it can result in many of the problems your son is displaying.
Sensory integration disorder is treated chiefly by occupational therapists, but the treatment cannot be viewed as something (at least in the case of serious level of severity) that will draw to a quick conclusion. Instead, it's helpful to view the treatment course as a progression of gradually developing skills and abilities. It's important to stay the course, assuming you've got in hand a reasonable assessment and diagnosis.