Have low back pain on the left side. the pain extends from left hip down left leg. no pain on the right side. pl advise?

Back pain: You need to see a spine specialist. This is an indicator that the there is pressure on the nerves coming out of your spine. This could be caused by a herniated disc or another issue creating undue pressure in the nerves.

Referred pain: Pain from inflammation in the lumbar spine often radiates down one leg. Doctors call this referred pain. If it does not resolve in a reasonable amount of time, you should see an orthopaedist.