It is important to confirm whether your daughter is having water urticaria or sweat urticaria. Water urticaria, or aquagenic urticaria, is a rare condition in which hives or itchiness develops within 1 to 15 minutes after contact with water .It is diagnosed by applying tap water and distilled water to the skin and observing the reaction.
For the itching antihistaminics like Benadryl and Claritin are recommended.Application of calamine lotion and mild steroids will also help in relieving the itch.Also use cotton clothes instead off synthetic and cotton blends.
If the symptoms persist then pls get it evaluated from a dermatologist.
I hope that helps. Please do keep me posted on how you are doing or if you have any additional queries. Kind regards.