Hydrocortizone cream. Stings a bit, but it usually stops things from itching. I always keep some in my backpack, and I usually take my backpack with me to most places. If you don't have any access to hydrocortizone, but do have access to a shower, a hot shower usually helps it stop itching for a while, too, but this is a very short-term solution. Doesn't work long. Other than that, you can try wrapping something around it, like a blanket, and then distract yourself with something. The blanket is to stop yourself from itching it without thinking, and the distraction is to hopefully get it off your mind. Obviously, this doesn't do anything to address the itch itself, but it can help you stop scratching for a bit. Get hydrocortizone, though.