What can be done about major back pain when sitting up straight?

Go see PCP: At 35-unless you have a history of recent injury or trauma, years of high intensity and high impact sports, or chronic heavy labor you need to be evaluated by a spine specialist if your pain is severe. Pain with upright sitting can be seen with arthritis in the weight bearing facet joints, but that's unlikely to be severe at age 35. Fractures and infection can point to other diagnoses at age 35.