Talk to Orthopedic Surgeon on Back Pain And Associated Involantary Body Movements During Sleep

My father started feeling severe pain in his lower back 5 months ago. It was so severe that he couldn't even attend his daughter's wedding. He was prescribed following tablets at the time for 15 days(1+0+1) 1) Omeprazole 20mg 2) Tizanidine 4 mg 3) Amitriptyline hydrochloride 25mg 4) flubiprofen 100mg Things got better with this medication but pain came back again after 2 months. After second pain attack, things got bearable on their own without any medication but it again came back now with high intensity. Now he's taking same medication for 3 days but having severe side effects with it. He's having loose motion and feeling sudden involentary body shivers during sleep. Pain is the same. Our concern is that we can't just go for pain killers to beat it. We need to diagnose its root cause so that pain can be prevented. Our request is to the honorable doctors here to guide us how should we proceed with the problem and what could be the possible cause of pain and sudden body movements. We w