I've had a hypersensitivity to high pitched noises and loud noises in general. It feels like electricity zapping through my brain. Any ideas?

Common in kids. Hyperacusis occurs frequently in autistism, adhd, hypersensitivity syndromes (like sensory guarding) & other developmental problems. If you've had this all your life it probably falls in this category. After your ENT appointment, if all is normal in your hearing apparatus, then you may wish to see a developmental physician or psychologist who can help with hypersensitivity problems.
?migraines? Consider getting evaluated from migraines.
Hyperacusis. This fact sheet by ENT specialists may provide some answers: http://www.Entnet.Org/healthinformation/hyperacusis-increasedsensitivity.Cfm.