Both conditions seem to respond to anti-inflammatory medications. If you haven't already tried this, ask your doctor if it would be a good option for you. If you've used a mild antiinflammatory with some results but want better pain relief, then a stronger prescription might help.
Exercise and activity are known to help with arthritis. Sometimes the movements that are good for arthritis flare up the stenosis. A physical therapist can help you learn what to avoid with each.
A more invasive treatment option might be spinal injections. Some patients get immediate and long-lasting relief with corticosteroid injections to the joints. Epidural injection of corticosteroids has also been used successfully with lumbar pain syndromes from spinal stenosis.
It takes time to sort out what works for each patient. Give each treatment option a fair chance. Keep a diary or journal of your symptoms, treatment, and activity level. See if you can chart improvements to help you find out which treatment or combination of treatments works best for you.