I've Been Feeling A Cluster Of Sharp Needle Pricking Pain

I've been feeling a cluster of sharp needle pricking pain in my head behind my left ear and then I feel the same sharp pain on my left shoulder and they will occur at the same time(like the nerves are connected), and its only on my left side, I usually get these pains every other month and it's been going on for about 10 years since I was young, have any idea what it could be?