I've been having short pains/sensations in my back and left side of my head, what is this?

Muscular or Nerves: Back and head pain can range in causes from muscle spasm to a "slipped disc." the location of the back and head pain would be important to assess to help determine the possible underlying cause. A more detailed story would help your doctor create a more concise list of possible causes.

High cervical nerves: "pinching" of the high cervical nerves can cause a similar condition. Would need a bit more information.