I had back surgery for L4-5 sixteen years ago. Had episodes of considerable pain which I dealt with (somehow). Then one morning the back pain disappeared and a pain like a flaming blowtorch settled in my left calf. It never went away.
Apparantly a piece of the disk had broken away and was pressing against part of the sciatic nerve. I started limping and had 'footdrop'.
Surgeon removed it in 20 minutes and the next day I was walking about perfectly and painlessly. It was truly miraculous. I have to be careful about sitting too much, lifting too much and vacuuming. Also doing exercises. If I do that I am fine, if not I will suffer.
You have to trust surgeon's opinion. Usually if pain has gone below the knee, it is a red flag. Mine would not do surgery if it was just back pain with no nerve involvement.
Hope this helps.