I've had the itch before and it's maddening. Mine is always in the center of my back.....that area right above the bra line that is impossible to reach unless you're a contortionist. I've also had it on my left arm. It's like an itch that can't be relieved by scratching. The only relief I got was if I took a Phenergan tablet and slept for half the day.

Hope you feel better soon.