I believe you are referring to spondylitis, which is an inflammation of the vertebrae of the spine. It generally starts out with lower back pain and stiffness, especially after periods of inactivity and sleep...ie., mornings are worse...as the day progresses and the person is more active, the pain lessens. It it strikes in the middle part of the back (thoracic) it can affect the rib cage and make it difficult to expand the lungs.
It is a type of arthritis that affects the joints of the spine, usually starting in the lower lumbar area and the sacroiliac joints (where the spine joins the pelvis). As it progresses it can work its way up the spine, and can eventually lead to the vertebrae fusing together.
This is a progressive disease, so it is important to see a specialist and to get ongoing treatment. The name for the disease is Ankylosing Spondylitis. You will be able to find specific information online as this is a specific type of arthritis and not just a collection of symptoms called "back pain."
Since there are a number of back problems that have similar sounding names (ie spondylosis, spondylolisthesis) that would require different treatments, be sure you have the correct diagnosis. If you have Ankylosing Spondylitis you will want to consult with a rheumatologist as this is a form of progressive arthritis.