A few things I’ve noticed over the years, dealing with my own allergies (including eczema/dermatitis):
I agree on the sweat thing. I go to the gym, but make sure I shower off every time, and apply lotion (I highly recommend Aveeno as the least irritating). It’s not so much that you shouldn’t ever sweat, but shower it off as soon as possible.
As for frequent showering, I’ve had doctors tell me not to use hot water as it dries out the skin even further. I could never manage to take a lukewarm shower myself; instead I made sure I moisturized thoroughly afterwards. But if she can limit the length of her showers to just what is necessary to get clean, that might also help.
Be careful with the corticosteroids, especially (in my opinion) with children. I believe they thicken the skin, and I have developed angiomas (benign tumors of the surface blood vessels) which are ugly and expensive to remove, in areas of heavy use of those medicines.
(Side note on dermatologists: the one I went to the longest always wanted to prescribe the strongest corticosteroid on the market. All that ever did was make it harder to deal with the next outbreak. I stopped going to dermatologists and stopped using prescription meds – except for Singulair, which I am very sold on --, and over time the outbreaks got calmer and easier to deal with.)
In line with minimizing sweat, minimize the polyester in anything that touches her skin. At least for me, cotton feels the best.
Clothes storage is important. Shirts especially are kept in plastic so they can’t get dusty. I always notice when I put on a shirt that has hung around outside of the plastic for a while - I get itchy for the first couple of hours.
For my skin eruptions, exposure to sunshine and fresh air work wonders. I think it’s mostly the sunshine. I don’t know why, but it works for me. I always suffer most in the winter when there’s no sun and I’m not spending any more time than absolutely necessary outdoors. When it gets really bad, I go to a tanning salon, which is almost instant relief.
I’m glad to read all the other advice, I think I’m going to try one or more of those anti-mite products for myself.
Roddy