Hello and welcome to healthcaremagic
I would keep a possibility of Acute
Urticaria. It presents as itching and skin welts/swellings, which can be distributed almost all over the body.
Causes can be-
-Foods and food additives/preservatives
-Drugs like pain killers, antibiotic, multivitamins etc
-Infections in the body elsewhere can give rise to urticarial wheals
-Urticaria due to changes in core body temperature (Cholinergic Urticaria) can happen in response to strong emotions, exercise, spicy food, hot shower etc
-Changes in ambient temperature e.g heat, cold conditions can also give rise to urticaria
An oral antihistamine like
Fexofenadine (180 mg) OR
Loratadine (10mg) OR
Cetrizine (10mg) once or twice daily for a week would be suitable.
I would advice you to get few basic lab tests like Hemogram, stool for ova/cyst, Urine routine, Chest X-Ray.
A topical soothing lotion like
calamine would help you symptomatically.
take care
Regards