Lower left back pain, tingling sensation and sometimes pain on left leg, what could be the problem?

Lumbar radiculopathy: Pain and tingling sensation down one leg with associated same sided low back pain is most often cause by a pinched nerve. Nerves pass through the lower part of your spinal column before entering and providing nervous supply to your legs. The nerve can get pinched or compressed, usually by an out of place disc, before they enter the leg. This can in turn cause the symptoms your are experiencing.

Back pain: The back pain can be caused by muscle strain, spinal stenosis, ruptured disc, nerve impingement ... It sounds like you are experiencing nerve pain. I recommend you seeking help from a pain management doctor or spine surgeon. You might benefit from a comprehensive evaluation and treatment.