Thanks for posting on HCM,
Your daughter might have contracted a fungi rash
which will require antifungi medication to treat it. Giving antihistamines alone without treating the actual cause would not work. If antihistamine has been administered properly and rash still persist, then allergy
might be excluded. Other medications such as oral steroid
can also get rid of allergic reactions when antihistamines alone fail.
Also possible are bacterial or viral infection of the palm skin most probably dermatitis
. Local creams (antibiotics, antifungal or steroid etc) could be administered to help deal with the affection. If rash persist, please do not hesitate to consult a dermatologist