Hi If we have constant nagging pain which is there for a longer period of time,it's a normal human tendency to adopt a body posture which will ease the pain,like limping or side bending etc. It will not be obvious to the patient but others can notice it. These postural changes creates undue pressure on others weight bearing joints, creating pain at other areas. So it can be postural pain or if mechanical ( due to disc or muscular), it can be differentiated only by a medical professional.