I remember that when I had a really bad pimple with cystic acne, sometimes one would itch as it was coming up, but not all over my face. Could it be an allergic reaction to something, like a soap or face cream? Even if you've been using it for a while, people can develop new allergies to things. Try switching to all mild and hypoallergenic products for your face for at least two weeks and see if that improves it. If the itching is really bad, try an over-the-counter anti-histamine, the pills, not the creams. A mild oatmeal-based lotion should help with the itching. If you do have acne issues, try to use only "non-comedogenic" products or ones that say they won't clog your pores.
If it doesn't get better, try seeing a dermatologist. If it gets worse before two weeks, you should probably see a dermatologist before that.