I have what feels like a muscle twitching/tingly sensation on the base of my skull (left side) for 2 days now. what could be causing this?

Skin tingling: Have a doctor look at the skin on your scalp. I always think of shingles when I hear this kind of story. Often the tingling feeling starts a couple days before the rash appears. This is the time to see a doctor, because the earlier you get started on the medication for shingles, the more it will help. After 48 hrs of the rash, the medicine doesn't make much of a difference.