Your daughter is most probably having urticaria/dermographism. In most of the cases cause is unknown however sometimes any particular medicine, food, worm infestation, house dust, pollen,change in temperature, cold stress
etc can induce the same. Whenever she has such episode, you can give her Benadryl
syrup. Also calamine
lotion can be applied to soothe the skin. At the same time, I would advise you to consult a dermatologist
so that proper evaluation can be done to rule out the underlying cause if there is any. Hope that answers your query.