Hi, visit nearby physiotherapy clinic for proper assessment and treatment,there might be so many reasons for ur back pain.
As ur doing a sitting job,try to maintain ur posture and ergonomics.support ur lumbar curvature while sitting for a longer hours.
If ur having pain or spasm take electrical modalities to reduce the spasm and pain.
After that start doing mobilization, stretching to ur back,later strengthening exercises
Next Steps
Avoid lifting heavy weights,prolong sitting and standing
Health Tips
hot/ice can be done 3-5 times a day,followed by stretching to avoid spasm.