Is this a sleeping disorder, or could it be all in my head?

I’ll explain this as well as I can…I do not normally sleep well, and I’m a night owl, so I have to take sleep aids to help me get to sleep. For years I’ve been taking Nyquil and nothing else. For as long as I can remember there are times when I go to bed and no matter how tired I am I can’t go to sleep because I start itching. Not just random ‘ignore me’ itches, but the kind that make you feel like you’re being bitten or poked with sharp objects. And I’m talking all over. Not all at once but like my arm will itch, I scratch and relax, then my foot, then my ear, head…just random places. And always I scratch and relax and another itch pops up. I don’t think it’s dry skin because I use lotion almost daily, and my sheets are clean. I never wear the same pajamas either so…what do you think? A sleep disorder or is it somehow all in my head?