Based on your answers, some of the most likely causes of your back pain include
disk disease
sciatica
spinal stenosis
spondylolisthesis
muscle spasm or strain or other minor injury.
Other, rarer, causes are also possible.
To decrease pain, avoid overuse and try over-the-counter pain medications, a heating pad or topical treatments (such as Icy Hot or Ben Gay).
While these measures may help, it is important that you see a physician if symptoms are getting worse or not improving over time.