The first thing to be certain of is that your symptoms are coming from the spondylolysthesis. Sometimes it's an "incidental finding" and not the cause of your pain.
For example, the tightness under your left foot is probably not coming from the spondylolysthesis. Only a very careful and thorough examination of the feet, hips, sacroiliac joints, L4 and L5 and in fact the levels above the spondylo can answer this. They may well be more than one problem level, causing some of your symptoms, but not others.
A major decompression of your back is probably waiting in the wings, and perhaps it can't be avoided, but I would certainly see a respected and thorough chiropractor first.
Every chiropractor treats cases of spondylo fairly regular, see http://www.chiropractic-books.com/Spondylolysthesis-CaseFile.html but where it's causing pain and tingling in feet and legs it's obviously not going to be straightforward whichever route you take.
Are you doing some disciplined gentle exercises EVERY DAY...? https://www.chiropractic-help.com/Lower-back-exercises.html
Then rule out plantar myofascitis in your feet.
Use the Search this site on the Navigation bar for more info on foot pain and spondylolysthesis.
I hope this has contributed.
Dr. Barrie Lewis