49-year-female assembly worker at automotive manufacturer presents to your clinic complaining of increasing back pain over the last week. Back pain is in the central low back region and radiates into both gluteal regions - no leg pain. Has been off work for the last 6 months with no improvement in pain. Create a list of possible differential diagnoses? Discuss the evidence you would need to obtain to rule in or rule out each differential? What additional aspects of the history and physical examination could provide relevant information to help in the diagnosis?