21 year old female presented with chief complaint of back pain for 13 days, radiating to the buttocks and occasionally to one or both legs, continuous in nature with no exacerbating or relieving factors. There was no preceding history of trauma or lifting heavy objects. Investigations were done and the patient was prescribed Tablet Etogesic -T (Etodolac and Tolperisone) BD for 10 days, with which the patient did not report any relief. The patient has now presented with similar pain of severe intensity from the past 14-15 hours. Kindly suggest Diagnosis and Differential Diagnosis for the same.