Thanks for consulting us.
There could be many causes of vulval itching including: vulval infection, vulval dermatoses
, vulval precancerous & cancerous conditions etc. It may be related to some systemic conditions or medications. However it may occur without any cause or you may have developed some form of allergy
Treatment depends on the cause & may need tests to find one.
Simply speaking you need a visit to a Gynecologist.
Hope you get well soon.