hi..thanks for the query..
The symptoms you mention seem to be a part of a disorder known as URTICARIA. this is manifested either for few days or months to years depending upon the severity. Altough it is not something that you should be very worried about, it runs a prolonged course of exacerbations and remissions in most cases. i suggest you go ahead with a course of oral anti histaminic medicines which are available OTC in most countries.If it is persistent over 6-8 weeks ,you might require a blood test
to be done.
In case of the hives
persisting 2 days, as you mention,it is wise to consult a dermatologist
and do a few investigations to rule out urticarial vasculitis
Observe your daily routine carefully..some people do see the lesions after stress
,having particular food, on exposure to a particular oral/inhaation/topical agent etc.
Hope this helps..take care!