Back pain can be because of Back ( Spine or Back muscles) and also because of
kidney diseases, prolonged sitting in a bad posture, even
Calcium deficiency, because of nerves, and in ladies because of Gynaecological diseases.
So you can imagine how many investigations you may need.
Next Steps
Please share a little more about your backache symptoms, and all the investigations you have done so far. Consult a General Physician or an Orthopedic Surgeon on Practo.