Pee, your poor little man. I swear by Tea tree lotion. Get it from suppermarket in a white bottle (like sun cream bottle flip top lid) I think it is in the natural med area. DH had pox when he was 25 and it did wanders. Stops the itch, keeps the skin moist but dries the spot out. dh recovered a lot quicker with it than what us kids did when we had it. The lotion is also good for sunburn and bites so you can see it moisturises and dries at the same time.

Hope he is not too miserable.