Remedy: Throw away your sunblock and take a walk in the sun!
The insides of my ears have itched like crazy since I was about 16, though I never knew it was psoriasis until almost a decade later. I just recently figured out that that was the age when I started to avoid direct sunlight and also wear sunblock constantly to prevent future wrinkles on my very fair skin--a practice I continued up until this year.
Avoiding the sun and living in an area with a far angle from the sun during winter months causes Vitamin D deficiency, which I am certain I had. Getting more sunlight by exercising outside in the morning has helped tremendously. Vitamin D apparently decreases cell turnover, including in the skin.
Avoiding a pro-inflammatory lifestyle and stress should also help, since autoimmune disorders such as psoriasis are modulated by inflammatory cytokines; in the case of psoriasis, interleukin-17 seems to be the problem.