I am 24, for the past 3 yrs I have had a sharp pain, once or twice a wk in my lower back lasting about 5 minutes and relived by not moving, any idea?

To solve a mystery, To solve a mystery of a 5 minute pain that happens once or twice a week, one has to write down on a big calendar: when it happens, exactly what happens, what makes it worse, what makes it better, what food/drink/meds he took that day, what activities/sports he did that day, etc... Take the diary to the dr. After 6-9 episodes, and the dr. Can examine the patient and test for the many possibilities.
Muscle spasm. Pain only lasting five minutes is not likely to be inflammatory back pain, kidney stones, broken bone, infection, cancer. A "pinched nerve" does not typically have these symptoms. Most likely it is muscle spasm. Get a referral to physical therapy or a chiropractor to learn what you can do yourself to lessen the recurrences of pain.