Ur back pain must be due to muscle spasm of back muscles. It can be due to postural issue so improve ur work related ergonomics like sitting and standing. Take small breaks after every one hour during work. Use Hot water Fomentation on ur back area. After getting some relief start stretching and strengthening exercises for back muscles. If still pain persist then visit to the manual Physiotherapist to get rid of pain and also to learn all exercises of back muscles.

Do the cat/cow stretch. Get on all fours, with your arms straight and your hands directly under your shoulders; your knees hip-width apart.

Don’t rely upon x Ray fully this is not a choice of diagnosis tool only In your case it just a muscle spasm which causing you trouble may be due to your job profile Need to fix it as soon as possible if this keep repeating this start causing the harm to internal structures because of disturbance of line of gravity and asymmetrical muscle function

Manipulative physiotherapist, Facet joint in lumbar Spine may be stiff causing pain.

Consult a physical therapy near by u for evaluation and further management

Meet physiotherapist now. Posture corrections must

It seems to be mechanical low back pain. Consult a physiotherapist for proper assessment and treatment.

Low back pain without a injury is mostly mechanical in nature. Consult a good therapist for proper assessment and subsequent corrective exercises.

You must have issues around your back muscles. It is good that your X ray was normal. If the pain is just in the back and not travelling to legs then definitely a Physiotherapist will be able to help you out.