Left hand fingers tingling constantly for weeks. tested negative for cts. primarily right handed so don't think it's overuse? anything to worry about?

Must have some cause: If an EMG was performed and showed no peripheral nerve injury then one should consider a central cause. This is particularly true if you have any symptoms in your left leg or face. If an EMG was not performed then pay attention to the fingers involved as the ulnar nerve could be the source and affects the last two fingers of the hand. Please consider meeting with a neurologist to get an answer.