While you don't mention how old you are, we are all familiar with the painful reminders that we get about our aging bodies. Cracks, in general, are not good things to hear. There are multiple things that could have been affected, but the fact that you don't mention difficulty or pain with breathing makes me think that you are not likely to have broken a rib. Those are extremely painful, and the soft movement of breathing is often nearly intolerable. The next idea, and the most likely, has to do with a minor soft tissue pull, such as a pulled muscle. Most of us are not as active as we should be, and sudden movements put unused and unstretched muscles under strain that they are not accustomed to, which puts them at risk for minor injuries.
The muscles of our back, often called the core muscles, are extremely sensitive to these problems as we age. Strengthening exercises and increased physical activity are the best remedies, as well as the best preventive measures, but you should speak with your primary care doctor
first if you are still in pain or have other medical conditions. Some over the counter pain remedies can also be very effective we used judiciously.