It could be anything from nothing at all, to an irritated area that you scratched, to a benign growth that you scratched to a skin cancer. Once something itches, then you can't even tell what, if anything, it was to start off with. My advice is not to worry (it's almost certain to be not much of anything), to keep the area covered with a band-aid so you can't mess with it, and to show it to a doctor. Bumps can't be diagnosed with certainty unless they're looked at in person.
Take care.
Dr. Rockoff