Lower Back pain-left side above buttock.

Hi, I have this lower back pain since last 6 months. This occurred in morning when I was keeping 4-5 liters of water can below and slide it through left hand and while other can was kept down already. I suddenly feel like trauma and dizziness for few minutes. I lay down and later realised that I was unable to move/getup. I was feeling so much of pain at that time( unable to do any activity). Consulted doctor, took medic and was better than before. But i am feeling this pain since then. Sudden jerk, coughing/sneezing causes the the pain.Some times the pain runs through my left leg. Through stretching and exercise there is relief. My job requires sitting at one place for hours. I don't know if it's nerves issue or slip disc. Can anyone guide how to check if it's nerve or slip disc at home through exercise or pose. The pain is mostly left side of leg above buttock. The right side is completely fine. Thank you in advance.