Looking For Non Opiate Pain Killer ( Owing To Chronic

Looking for non opiate pain killer ( owing to chronic constipation with paradine fort etc ) condition is wide spread arthritis in lower back and deteriorating facet joints in a few visits to hospital for back spasms Diazapam and morphine injections and endomes get me back on my feet but again constipated.all Most of my pain is mechanical I am seventy years old. Thank you.Richard ?