Hello,
It can be due to hives or thyroid disorder as thyroid diseases are often accompanied by itchy skin. It can also cause parasthesia which some people interpret as itching sensation inside the skin. Regarding the hives before periods. Ovulation and menstrual cycle are two such phenomenon which is associated with rapid hormone changes every month.
To stimulate ovulation, progesterone levels increase while estrogen levels decrease.These hormonal changes cause the body a great deal of stress and stress is one of the important factors thought to be causing hives.although urticaria usually is idiopathic,but stress is an important causative factor. Regular medications with antihistaminics and steroids during hives flare up has shown that in approximately 75% of patients, chronic hives are found to gradually or spontaneously diminish within 6-8 months. In 90-95% of cases, the symptoms disappear within 2 years.
So please consult a dermatologist and get prescribed antihistaminics. Also start the treatment of thyroid disease. I hope it helps. Take care and regards.
Thank you very much for the information and your help.