Your symptoms have been present for six years now, so obviously it is a chronic process. Back pain and stiffness of the back are very common symptoms in a large number of people. The common causes for backache are spondylosis, which is age, related (unlikely in your case as you are young) and disc prolapse. Disc prolapse may occur in young people but the pain is typical with radiation down to the legs may or may not be associated with numbness and tingling. Rest always relieves it. The other cause for chronic back pain in adult male patients could be ankylosing spondylitis. This could also have associated morning stiffness. This can be diagnosed by careful clinical examination. Postural pain because of bad posture is often implicated as a cause of backache. However, there is always some underlying cause either in the structure or in the formation of the spine that contributes to this.
The key to good management is to pinpoint the exact cause. From your history it is very difficult for me to do that. I would recommend that you get yourself examined by a competent orthopaedic surgeon and let me know the findings and observations. I will then be able to guide you in a better way.