It sounds that she may have a case of ECZEMA as the case of her rash...
This is a combination of DRY and hypersensitive skin.. giving an allergy like response...
She may respond to a combination of a moisturizing lotion ( one with aloe is soothing) and a low potency steroid cream such as 1 percent hydrocortisone applied to the rash ( both twice a day )
Sarna lotion for sensitive skin is a good product for this condition..
You are welcome to include pictures which may be helpful to solidify the possible diagnosis ..
If she does not respond within a week to 2 weeks of treatment OR it is getting worse then she should consult a dermatologist.
She also would benefit i think to try an oral antihistamine such as OTC Allegra or Zyrtec ( certrizine) or benedryl ( more drowsiness and needs to be more often with the Benedryl)
She should avoid scratching ( rubbing a wet washcloth dipped in ice water is helpful for itching as an alternative to scratching and the cold reduces inflammation... )
I hope that this information is helpful for you.
Let me know if you have further questions or concerns.
I will be happy to get back with you!
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Thank You and Best Regards,
Anthony Bray MD