I have some spinal stinosis in the lower back. When I walk it hurts mainly on my left side.?

Stenosis pain is . Usually pain into the legs standing or walking and relieved by sitting or bending over. It can affect one or both legs. There can be back pain related to the changes that created the stenosis or unrelated to it totally such as hip arthritis or a sacroiliac joint problem. If problematic, see an orthopedic surgeon as to cause and appropriate treatment.
Physical therapy. Physical therapy may be helpful. The best thing for spinal stenosis is exercise to strengthen the paraspinal muscles that support the spin. It may hurt to do the exercises at first, but it will be worth it in the long run. Also if you are overweight- try to get your weight down.