Most back pain goes away on its own, though it may take awhile. Taking over-the-counter pain relievers and resting can help. However, staying in bed for more than one or two days can make it worse.
If your back pain is severe or doesn't improve after three days, you should call your health care provider. You should also get medical attention if you have back pain following an injury.
Source: NIH – National Institute of Arthritis and Musculoskeletal and Skin Diseases