I have a 6-yr-old with CAH...she has not had chicken pox or shingles yet. I had shingles when I was just a bit younger than your son...I think I was about 10 or 11. A few years ago, I had shingles again. It lasted a few weeks both times. Oddly enough, my daughter with CAH apparently CAN'T get the chicken pox!...she's been exposed so many times.....including playing with nextdoor neighbor twins with chicken pox...and she still hasn't gotten it. My having shingles around Christina still didn't make her erupt in spots (which, it's my understanding, can be the case since it's the same virus). Apparently, this is going to be a thing with your son....I'd bet somewhere down the road as an adult, he gets shingles again. I've known other people (non-CAH) that have done the same thing. Good luck...I hope it goes by quickly for both of you!