hi i had gone through your query and understand your concerns. i would come up with the possibility of 
ALLERGY -
URTICARIA is the cause for your sufferings.
-Allergies are defense system over-developed by the body to give warning that its metabolic system is unable to handle a substance in a normal manner.
the possible causes allergy  include;
-genetic predisposition
-emotional stress
-internal diseases
-physical factors like heat,
cold,sun,exertion,pressure,vibrations etc
-immune regulation defects
-food and food additives
-drugs
-insect bites
-contact plants
-intestinal worms
treatment option;
 i advise you taking   
Homeopathic medicines gives  safe and permanent  cure for your complaints along with management
consult your local homeopathic physician for correct diagnosis of the case and remedy to fit your complaints 
I hope this is helpful for you, thank you