Thank you for your question. From your description, it sounds like you are experiencing back pain. Back pain is a common complaint and is one of the most common reason that people visit physicians in the United States. You should see a doctor
for an accurate diagnosis.
There are many causes of back pain. One of the more common causes is spasm of a muscle in the lower back. This can result from minor injuries or from straining, such as from lifting a heavy object. Oftentimes, people with this condition will assume abnormal postures to lessen the pain they feel.
Another relatively common cause of back pain is a problem with the disc or discs that are located between the bony vertebrae. In some people, discs can "herniate" or lose their normal shape, which can cause pain. The most common discs to be affected in this way are in the lower back. This can either cause pain directly at the site of the problem, or referred pain - such as in the leg.
There are many other causes of back pain, some of which are serious, such as infections, fractures, or tumors due to cancer. It is impossible to receive a diagnosis without seeing a physician. I strongly advise you to see a physician.