I had 2 lumbar fusion surgeries with a lot of hardware. I have left with nerve damages.
I can relate to what you describing. This seems definitely nerve related issues and I would consult my Spinal Ortho or Neurologist.
They may perform EMG test on you to determen if you have any nerve problems.
Meanwhile you "listen to your body". notice what exactly and where that feeling of numbness travels too that when your DR asks you - you have answers for him.
Best of luck to you and take care!