Don't panic... I do not believe you have a ruptured disc like one may have mentioned... Its possible but I would be much more concerned if you had any change in bowel/bladder, leg weakness, numbness/tingling, etc. Make an appointment with your primary care physician... from there he/she will take an X-ray, send you to physical therapy (my job), from there you either get better if it is muscular, or if PT fails, they will send you back to your doctor who will then order an MRI and send you to a spine specialist...
Hopefully a PT can fix it.. if you have any specific questions feel free to PM me