Funny you should ask, because just yesterday I was reading a New Yorker article on the subject, and the researchers said that pain and itch are definitely different pathways.
“You can trade pain for itch, Dong points out: that’s why mice and men both scratch. But it won’t work the other way around: you can pain your itch, but you can’t itch your pain. A signature of itch is that it’s specific to the skin. Your bones can ache, but they can’t itch.”
http://www.newyorker.com/magazine/2016/05/16/what-the-science-of-touch-says-about-us
