My scalp has been painfully itching for the past 6 months, please help me.

[aearachi]

Around January, for 3 straight weeks I'd wash my hair with 2 eggs, once each week. I stopped after awhile, and somewhere around in February i started to pick up this constant and unbearable itching in my scalp, but other times it can be on my upper neck, or behind my ear. I've used 14 different dandruff shampoos, even one that warned of "can cause cancer in the state of California" yet absolutely NOTHING has shown to work. I've been checked for lice 8 times and so far, nothing.. I don't know if it could just be fleas or what but it's absolutely terrible. I've itched for hours at a time, and sometimes it will go away, but it always comes back. Other times I've experienced it to not come around for a couple of days before striking in the worst situations, i.e. in public, family reunions, school, etc..
It was also in January I was diagnosed with generalized anxiety disorder and I was wondering if that had anything to do with it? My friends just tell me I'm delusional and it's all in my head but at this point I can't stand this anymore and I'm in desperate need for some kinda relief.
I've noticed that it can sometimes start itching whenever I go outside, but it can itch just about anywhere. It's itching right now and I'm inside.