About a dozen years ago, my lower back pain worsened until I awoke one night with a fiery pain shooting down my right leg to my middle toe that wouldn't go away. Worst pain I've ever experienced. Xrays showed nothing, but MRI showed a herniated lumbar disc (L4 or L5, can't remember). Neurosurgeon advised trying PT and then call him if I wanted surgery.

It took a few weeks of intensive therapy to move the pain up the leg to the hip, to my back and finally to subside. I never fully got feeling back in my foot. I have been able to keep the bulge in place by periodic exercises whenever I notice pain starting to return. I was off the bike for a few weeks, but soon was able to ease back into road riding and eventually mountain biking. I found that the more I ride my road bikes, the better my back gets. I now ride for hours on dirt/gravel roads without back pain.
YMMV.