I have constant lower back pain for many years. What can be the cause?

Hi doctor,

I have seen many doctors regarding lower back problems since the past two years. I have had two courses of physiotherapy with no real improvement and cortisone injections, which also did not help. I have also had two computed tomography (CT) scans and an magnetic resonance imaging (MRI), and I have attached the reports. I am also prescribed Tramadol 50 mg and Celebrex 100 mg. I first noticed lower back problems in my early 20's, when my work was heavy labouring. I continued this type of work till my 40's while also working in my current job as a career in an aged care facility. Over the years, I started to experience leg weakness and continued lower back pain and stiffness, which is worse when I get out of bed in the mornings or after long hours of walking and standing at work. Also in the mornings if I sneeze, it causes a severe and sharp pain in the lower back, so when this happens, I bend over with hands on my knees and brace for the sneeze. Several times a year, the pain and stiffness would become severe and after several days subside. My lower back problems started to get worse earlier this year. And last month, the pain and stiffness became severe. The pain level would have been 10 out of 10, and I had problems getting out of bed and needed someone to help me get dressed or sometimes putting footwear on. It was difficult to get out of chairs or sit due to the pain and stiffness, and walking was very difficult, I also had great difficulty getting in and out of cars. The Tramadol I was taking had little impact on the pain. During this time, I continued to attempt short walks and do gardening and household chores. Then by about a few weeks back, the pain subsided within a few days back to the usual morning pain and stiffness, which I would rate about 4 or 5 out of 10. I have attached all my reports.