What PUNKEY stated above makes lots of sense, because my scalp also gets irritated by certain shampoo's, ever since i became more aged.
...But also i'd immediately rule out possible viral or bacterial or Lyme infection via the correct type of doctor. Then i'd try keeping away from all electronics for awhile, to see if during that period you feel better. During that "test" period, i'd also stick to the most mild foods possible, and try to avoid chemicals.
I know y'all will laugh at this, but if it were me, i'd try to research & find a reputable medical intuitive if doctors haven't helped you. Or if i had money to spare, i'd fly to, say, Hungary, and get diagnosed via the SCIO, which is officially called "biofeedback" but which actually is one of the most accurate forms of diagnostics. Though by now there may be others even better. For example, the Russians had long ago come out with something called ROFES.
The reason you hardly hear about these things, is because anything that's not mainstream usually gets scant notice. But that doesn't mean they're not more meritorious than mainstream. Just look up thrivemovement
to get the gist of what i mean.