http://www.members.cox.net/yadhelp1/yadindex.htm
the yad part is youth with addisons, it is a small page but it does have someone on it who is young (teenager) with addisons.
Also nadf (great site for links, articles etc on addison) has a kid pen pal group
http://www.nadf.us/links/penpal.htm
It is frustrating and a story you will see over and over is how people were not diagnosed for such a long time. It seems like the drs want to test for everything in their standard care pocket guide but never think of looking for the zebra. Addisons disease is a “zebra”, considered rare yet the tests to diagnose it are so simple. Getting onto other websites and support groups is the best way to get information and find out if your nephew needs to tweak the treatment and medication he is getting.
There are some great books about “chronic illness” too not that we would get told that is what we have but if you check some of them out of the library there are a few nuggets to coping, dealing with drs etc in them.