With the description that you have provided, it seems to be hives
In children hives could be due to urine or stool infection so get a routine and culture sensitivity tests done for the same. Sometimes parasite infestations also lead to the same. All this will be ruled out by above mentioned lab tests. Particular food allergies
, sour food, preservative based food like jams sauce and pickles too can cause hives. Having said this, unfortunately in majority of cases there is no underlying cause for hives. It subsides on its own. But for symptomatic relief and to prevent recurrences, it is better to keep your child on medication. There are antihistaminic a like fexofenadine
with least side effects, you might ask your doctor to prescribe those. Hope that answers your query. Take care.