The Ready State Virtual Mobility Coach is like having a virtual Kelly Starrett in your pocket.
if i were to take a guess at only what you describe, i would say that your left glute has some dysfunction. the evidence would be the tightness/spasms in the low back and leg. with your glute out of the kinetic chain, your low back and your hamstrings compensate for the lack of glute involvement and take up the load. without the glute, they will overload and produce symptoms like yours.