Back
Is it hard to get out of a chair or pick something up off the floor? Do you get pain getting out of bed in the morning? Does it hurt to cough or sneeze?

All of these questions help you determine which structures might be causing your back pain.
Your body is a balance between stability and mobility, so if your thoracic spine (mid-back) is too stiff then your lumbar spine (lower back) can become hypermobile (too flexible). This puts extra stress on your lower back structures and your body will respond with protection by limiting your range of motion or ability to bend down.
Sometimes you can get symptoms further down your leg, which could be compression of the nerves in your lower back from inflammation of a joint or disc. Pain getting out of bed in the morning, sitting poorly then pain standing up and painful coughing or sneezing can be indicators of lower back inflammation.
Ensuring your back rests in a neutral position by using a small cushion or rolled up towel when sitting, can greatly assist with decreasing inflammation. Also, stretching your thoracic spine and hips to increase their mobility can take some stress off your lower back and allow you to focus on strengthening your core.