Lower back pain...stiff neck that goes away when i move it ...on and off mild headaches....jaw pain ...feel heartbeat in my back...what could this be ?

Various symptoms: I doubt that these varied symptoms are interrelated. It's best to have a physician take a thorough history and system review, perform a physical examination and order any appropriate tests in order to make a diagnosis. Low back strain, temporomandibular joint dysfunction, tension headaches, prominent aortic artery pulsation with or without aneurysm come to mind. Your MD will sort all this out.