LizChristine,
I know that I have had a problem with dermatitis that sounds a lot like what you’re describing. I have SWCAH and I get it a lot in my elbow area. My mother always told me to use cortisone cream and that is what has helped me with my rash. I cannot see what your daughter has, so may be wrong on whether or not she has dermatitis. I just know that I get this a lot and I think that its a part of the CAH. I hope that this helps, but if not, I hope you can find the answer. You can always ask her endocrinologist or find a primary care physician who specializes in the known of all these problems.
Liz