I understand your concern since your son must be in considerable discomfort. However what he has is known as Acute Urticaria, also called hives. This is a skin reaction pattern caused due to histamine release in the skin and can be caused due to a number of underlying reasons. In children amongst the commonest are intestinal worms and recent infection (e.g viral fever, cough & cold). In most cases acute urticaria is self-limiting with in 2-6 weeks.
I would recommend deworming your son with Syru ...
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