There r multiple situations in which one can experience such pains increased during morning. Occupational problem is one of the main cause due to prolonged sitting in same posture, certain medical conditions need to be ruled out like ankylosing spondylitis which also has symptoms more around  morning time, If the X ray is not able to pin point to any specific diagnosis it's better to get clinically evaluated again. U may be required to undergo a few tests or physiotherapy depending on your clinical findings.... Hope u recover soon. But please maintain good back posture.tc.