Always look *internally* for a cause first and foremost. When it comes to itchy face as opposed to more whole-body itching, some kind of microbe imbalance is usually involved, so your protocol should include probiotics - kefir, yogurt, first and foremost, possibly Primal Defense too.
If the itching is more whole-body, then it usually ahs to do with the kidneys being overloaded and electrolytes being all wonky. But I think with your case it's mostly a weak immune system that is unable to deal with microbe colonies fighting with each other. Strengthen the good guys and they'llt ake care of the bad guys and things should equalize. Take care of the bowels and lymph like Invincible suggested and that will help too.