Since you have a history of lower spine fracture along with vitamin D deficiency, your backache may be due to bone weakness and strain on the spine. It is important to continue vitamin D treatment if advised and ensure adequate calcium intake to strengthen your bones. Along with this, follow spine-friendly habits such as avoiding heavy lifting, maintaining good posture, using proper back support while sitting, and doing gentle physiotherapy exercises to improve strength and flexibility. If the pain is persistent or severe, consult your doctor.