Welcome to HCM,
Apart from Hypothyroidism
,you are having urticaria for last 7 years, I am sure you must have been investigated by proper tests. Hypo thyroid itself can cause dry skin and urticaria.
Your urticaria could be due to some allergy or autoimmunity? if no cause is detected for allergy it is idiopathic.
Antihistamines give symptomatic relief like Levocetirizine
but you should meet good Dermatologist
and investigate to try to find cause like serum IgE level and allergy testing in vitro if any allergen is detected and if it can be avoided or can be desensitized with immunotherapy
then it can be treated.
Sometimes sedating type of other prescription anti allergy work and if required combination with other drugs which also have anti allergy property.
Even parasitic infestation could be cause in some.
if severity of symptoms short course of corticosteroids
helps to control the symptoms . you must take proper prescription .
Hope this helps.
Dr.Akhilesh Dubey M.D.