My daughter just turned 11 this month. She was diagnosed at 3-1/2. She is not a salt waster. We have over the years seen her experience fatigue as you describe. Usually it is after she has been playing sports, doing something strenuous, or if she is sick or getting sick. I would think this definitely has "something" to do with the CAH. Generally, this is one of the signs I watch for and when I see it I either boost her hydrocortone or give her lots of Gatorade and salty snacks. Even though she is diagnosed not a salt-waster, she takes Florinef and the dr.says she may lose more than a normal amount of salt at times.