I have a pain on my lower left back side. it comes and go. it can be mild but sometimes my left leg goes limp and i fall. when i fall it hurts to move?

Radiculopathy: It sounds like you have a lumbar disc herniation with nerve root impingement. Although it is not in emergency, I would consult with a spine surgeon, get in the Marais and receive appropriate treatment which mean clued steroid injections, physical therapy, anti-inflammatory medication.

Sciatica: There are multiple potential causes, but among the more common is a "sciatica" which is an irritation of a nerve in the back that then causes pain to run down the leg. I would not hesitate to be seen for a specific diagnosis and treatment options.