hello .thanks for your query..
Your daughter might be suffering from Urticaria
.It is common condition of the skin with frequent exacerbations and remissions.
In most cases,a direct cause is not identified.However a combination of correct anti histaminic tablets for a few months help in reducing the severity and frequency of these hives
. In certain cases, a few bood tests are advised to rule out ant internal causation of the same.
Start application of a soothing anti pruritic calamine
lotion to relieve the itch.Observe if having anything/doing anything aggravates this.Eg,Some people have urticaria on taking warm water bath ,etc.
Do not worry;although this is a persistent condition, and will take time to improve/resolve.
hope this helps!take care...