Hello !
Have you changed your mattress recently ? Look up your daily routine and try to find out what changes have you made in your lifestyle , in terms of physical activity.
Cracking o the back, most often triggered by stiffness in the bones and muscles of the back , could be easily caused by assuming postures of prolonged immobility , e.g. long distance driving , sitting for very long hours , or even sleeping incorrectly, on mattress which doesn't support your back well, OR if you have stopped any kind of physical activity that you were doing earlier , or even if you have suddenly started a new physical activity , causing post exertion stiffness !
Again , cracking of the bones , in the long run is not a healthy habit . Even though it gives temporary relief , it will cause recurrence of pain / stiffness and perhaps aggravate problems in the long run.
Also keep a lookout for the progression of your problem e.g. is there pain , or any other associated symptoms ?
Observe your daily habits for some days and of the problem persists , its good to have it evaluated . Issues related to general body stiffness can easily be sorted out with a guided regular stretching and flexibility program for your body , after consulting your physiotherapist. Tc.