Hi. Thanks for posting your concern at HCM
Urticaria OR hives can occur due to various causes like(to name a few) infections(bacterial, viral, fungal), drugs, certain foods, cold temperature, in
autoimmune disorders like SLE, RA etc. A few cases have no underlying cause and are known as idiopathic urticaria.
In children intestinal worm infestation is an important cause, so is Atopy (raised IgE levels against common allergens in the environments like house dust, animal dander;
hay fever and asthma)
I would advice you to get few basic lab tests like Hemogram, stool for ova/cyst, Urine routine, Chest X-ray.
An oral antihistamine like
cetrizine OR
Hydroxyzine once or twice daily for a week would be suitable.
a topical soothing lotion like calamine would help him symptomatically.
take care
regards