I heard a study about itching. The more you itch something, the more itchy it makes it. It doesn't help the issue. So, the more you itch it, the itchier it gets.
I don't know how to break the pattern, though. Put something on it that hurts? When I get poison oak, which is the worst torture ever for me, sometimes it itches so bad I put bleach on it. The searing pain is preferable to the itch.