As per your symptoms it is likely due to a lumbar spondylosis associated with a prolapsed intervertebral disc or a similar cause which is leading to nerve root irritation in the back and you have a radiating pain in the distribution of the nerve. Likely cause can be pointed out using an MRI of the lumbo sacral spine and consultation and examination by an orthopaedic surgeon. Usually people with a long sitting job sitting job and chronic bad posture are likely to suffer from similar symptoms. Muscle relaxants neurosedatives, neurotonics and rest with hot water fomentation will certainly help.