What Causes Severe Itching Around Labia Majora?

hello, i have had an intense itch around the labia majora, at first i thought it was an yeast infection so i used monistat to treat it, then it had gone away for three weeks then it slowly came back. The skin down there is very sensative so i use hyperallergenic soap with no perfumes and i am currently using monistat itch relief cream to try and control the itch it has been three months and the itch comes and goes. i have set an appointment but i would like some suggestions as to what may cause it?