I get the same thing happen to me. Sometimes I get sudden, quick pin-prick sensations in other areas, as well...like the side of my head, my arms, legs, and my back. This sensations is definately nerve-related. It can be caused by many things, though. If you have compression somewhere in your spine, due to things like disk herniations, cysts, osteophytes, etc...those things can press into surrounding nerves and cause nerve symptoms and/or pain.
I have been taking Lyrica since last February to try to control some of this pain. It does definitely help me, though I still get some bouts of severe sciatica and other nerve pains. But it still helps b/c when I was out for several days waiting for a refill, it got worse.