Usually the muscles are merely out of condition and have allowed small ill-defined injuries or strains to occur. X-rays are needed only in the aged, in those with a long duration of symptoms, with unequal knee or ankle jerks, abnormal lab tests, and in those with point tenderness over the spine. Some people get so distressed that anti-depressive medication can be invaluable in their return to normal. Doctors need to recognize that. Stressful life events, such as family crisis, mental or employment problems, may lead to pain in the back problems.
Fever is a danger signal too.
Perhaps you get no relief by lying down or you cannot lie still. Change in bowel or bladder function or increased pain on coughing or paralysis will cause worry in the mind of your doctor. The cause of your backache may be something serious within or outside your spine. It might be a penetrating peptic ulcer or an inflammation of the pancreas. Don't tough it out.