As mentioned above, your back is a complex set of vertebra and discs. The constant stresses placed on this system daily affect its proper alignment. This is why I am a believer in chiropractic, the area of the medical community that deals with the mechanics of the spine. A very informative site about chiropractic is At YourSpine.
Everybody pulls a muscle. Everybody sometimes gets the pain and stiffness the day after exercise. Indeed, the bodybuilding community uses the phrase "No pain, No gain" to describe the consequent pain and stiffness associated with the exertion levels necessary to build and maintain muscle. If you don't have any pain or soreness the next day, you didn't train hard enough. I say "Feel pain, Refrain!". The muscles of our back, particularly the lower back, are especially susceptible to this exertion and resultant pain.
The Vitamin C Connection discusses the effectiveness of vitamin C on muscle and back pain. I.H. Syed in London describes his experience with C and muscle pain an stiffness:
"that muscle stiffness and pain which arises after exercise or an unaccustomed work could be prevented and treated by taking massive doses of ascorbic acid". His treatment was 500mg before exercise and 400mg afterward, along with plenty of fluids. If discomfort still occurs, Syed recommends another 400mg in the morning and one or two doses of 200mg every two hours if required.
Another study looked at patients undergoing procedures involving instruments placed drown the throat. These procedures produce trauma to the muscles lining the throat, causing pain and soreness. The results are shown below. The most statistically significant result is the difference in the number of patients reporting "severe pain", 37 versus 5.
Vitamin C may be effective for several reasons. The most obvious is in the development of collagen which is the foundation of the extra-cellular matrix, the glue that allows cells to form tissues. This extra-cellular matrix is dependent on sufficient vitamin C for its proper formation. This is particularly true of tendons, ligaments, intervertebral discs and other tissues subject to mechanical stress (this is why there is such a strong link between C and atherosclerosis). Adequate C will produce better muscle tissues in the first place and will also aid in their healing when they are damaged. The damage from exercise also produces toxic waste materials. Vitamin C may aid in the quenching of these toxic materials and also may aid in their elimination due to C's diuretic properties.