Two or three years ago I deeply scratched my leg when I ran into a stubby branch on a fallen tree trunk. I was wearing shorts. I never covered or even cleaned the wound. About five or six days later it started getting red. I went to the docs and got some antibiotics for it. It cleared up, started to heal and started to scab. About a month or month and a half later it began itching and I started getting little raised red bumps on the entire shin area. I occasionally relieved the itching and bumpiness with tea tree oil. But it would always come back. Then, one day, after about 6 or 7 months, it just went away for good.
If your itchiness persists, I recommend tea tree oil applied to the affected area once or twice a day.