I have itchy skin also and tried organic soaps but that didn't work. I use a body wash instead of soap and shower with cooler water. Don't get it too hot and try not to stay in too long. I also use baby oil while I'm still wet to lock in moisture. A good body lotion is also important after you dry off.
I know it sounds like you need a lot of moisturizers, but it really helps to reduce the itch. For my scalp I use Nature's Gate tea tree shampoo and conditioner. It helps to reduce scales and itch. It calms the scalp. The best part is it doesn't fry your hair. Many shampoos that reduce itch are not good for your hair so it ends up brittle and dry.
I think you can find this shampoo on-line or at Amazon.com. It's worked for me.