I am having shooting pains down my left side and leg following a discectomy, before the op i had little pain on the left side and i just wondered what could be causing it. also weakness appears to be worsening in both legs.?

See your doctor now: If you are experiencing weakness, this is an emergency. You need to go to the nearest er.

Several reasons : You may have reherniated the disc to the left side which is a 5% risk or you are developing or developed a hematoma or fluid collection post op placing pressure on that side which unlike the right side still has a "roof"!or covering on it that may not allow for any release. There are other possible reasons so you should discuss this with your surgeon.