I have back.pain and stiffness early morning. why?

Best to See a Doctor: There are a number of possibilities. It may be as simple as muscles tensing all night while you sleep, giving you a stiff back in the morning. It can also be signs of a spinal form of arthritis, known as seronegative spondyloarthropathies (isn't that a mouthful!). A rheumatologist or a physical medicine ; rehabilitation doctor would be your best bet!