My guess would be that it is a skin syndrome similar to excema...It's called KP or (keratosis pilaris) and it's caused by the skin not sloughing away quickly enough near a hair folical and then creating a cyst or white-head. Your best treatment will be to wash using only cetaphil cleanser or something for sinsitive skin and to mix ultra healing Eucerin (it has alpha hydroxy acid in it to gently slough dead skin cells) lotion with hydrocortizone 1% percent creams in equal parts and coat her in it twice a day on the affected areas.
On myself I use nutrogena body scrub to slough the skin then I use my lotion mixture.
For the lotion I use hydrocortizone CREAM and put it in a small travel size bottle and fill it halfway, then I put the lotion in on top and mix with a plastic knife or handle end of a spoon until it looks mixed well. Then I use it on a daily basis...I have three or four bottles of it...one in my car, one in my husbands, one in the bathroom and one in our travel stuff...I always have one handy, and since it has hydrocortizone in it it's good for bug bites and sunburns too.
I have it on my thighs (front and back) and on my forearms near my elbows. My daughter however has it over her entire back, the backs of her thighs and her face. It is sometimes called "chicken skin" disease because it can cause the skin to look like chicken with the skin on would.
I would try some other tips at http://www.helpforkp.com
M. (feel free to email me -- ____@____.com)