Thanks for posting your query. It seems that you suffer from a condition called urticaria
. It could occur due to so many reasons like infections, inhalants, infestations, implants, injections, instillations, inhalation, auto immune and idiopathic.
In your case sine you have cold
it could be due to pollen inhalation or due to infection.
These episodes usually disappear with a course of anti histamines
for one month or so.
If you are not better and suffer from this,even after four weeks please consult your dermatologist
and you have to undergo blood tests to prove the cause and eliminate the culprit if possible.