Back pain in mornings. This problems.

Hello Doctor, After sleeping for five-six hour it becomes difficult to remain laid horizontal on bed because my back hurts very much in the morning. It pains me in spine, approx. 1 feet above lower end of spine. Back side of the place where rib cage ends. It pains more if I sleep with my face up. Sleeping on side ways pains less. Surprisingly nothing happens throughout the day. After I wake up and sit down the pain remains for few minutes and then it's gone gradually. I have tried different mattresses, different ways but the problem seems to be increasing these days. This started happening when I bought a new form based mattress of high density 2 years back. Since then I have changed the mattres but still it's the same. Now it pains in everything morning. Please suggest me proper actions for this problems. Thanks for you time. -- Vimal