What could cause a tingling in the fingers of my left hand that wont go away?

Nerve Impingement: Depending on which fingers are tingling, it could be different nerves which could be compressed anywhere from your shoulder/neck area to your wrist. We would need more details to give you more specific advice. Generally though, this could be due to sleeping in a restrictive position, typing on a computer all day, tight muscles, etc. Take note of anything you may be doing that triggers the tingling.

Maybe carpal tunnel: Pressure on the nerves at the level of the wrist, or higher up can cause these symptoms. Can be a repetitive stress injury from keyboards, etc. See your doc.