I suspect that the doctor will diagnose him as being on the spectrum. However, I would address environmental issues to ease things for him as well. As a previous poster suggested, Omega 3s might be a good idea. Also, if you aren't already doing so, a change in diet might make a tremendous difference (if you're interested, I'll be happy to post more).
As someone who "hears" electricity, I can tell you how nerve-wracking it is. I, as an adult, have cried when I couldn't sleep because of it. Both ds and I hear it, but dh doesn't. Do you have power lines nearby? Do you keep your cell phones on? Do you have Wi-Fi? Did you recently get a Smart Meter? All of these things can make his problems worse.
We live near large power lines, and when ds and some friends were playing close to them one day, they actually made ds's jaws clench and hurt; he now knows not to go near them. Because of this and many other reasons, if we could afford to move, we would.