Hello and welcome to healthcaremagic
You mentioned it rightly,seems to Urticaria
the way you describe it. It can presents as itching and skin welts/swellings, which can be localized to a particular area or they distributed all over the body. The lesions are evanescent, and they rarely last for more than 24 hours
Urticaria OR hives can occur due to various causes like(to name a few):
--Infections(bacterial , viral, fungal)
--Drugs(Pain killers/ antibiotics etc)
--Certain foods and food additives/preservatives
--Physical Urticaria: Cold temperature, Heat, Pressure(Prolonged Standing, Sitting), Dermaographism etc.
--Cholinergic Urticaria: in response to strong emotions, exercise, spicy food etc
like SLE, RA etc.
--A few cases have no underlying cause and are known as idiopathic urticaria.
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 Fexofenadine
(Allegra 180 mg tab) OR Loratadine
(Alaspan 10mg tablet) once or twice daily for a week would be suitable. They are non-sedating and wont affect your alertness level.
A topical soothing lotion like calamine
would help you symptomatically.