I had staph infection a while ago and it was treated. However, my ankle (the original site from which it spread) still itches. Is that normal?

Sort of. It is likely that there was a sensory nerve located in the area of the infection. The inflammation, and/or any treatment to the area for infection likely irritated this nerve. Now, you are having a neuritis to that nerve, which can cause various stimuli such as itching, burning, temperature change, etc.