What Causes Numbness And Tingling Sensation In The Legs?

I ve recently doctored for pain in my left leg as my symptoms are tingling sensations and numbness which has been going on for 1 month or more. A lumbar spinal MRI did not confirm it was a nerve problem nor did it show anything else. I recently in the last couple of days have some mild pain or discomfort in my lower back. i A nerve conduction test was recommended next but with the lower back pain my doctor is thinking of some kind of spine test (can t remember if it s an x-ray). My symptoms has not prevented any activity other than bowling,