I get lower back pain too. Im 15, I have had it for about 5 weeks now, my dads side of the family suffer from back pain but not until they are much older. I went to see somebody about it and they told me i have an inflamed disc in the bottom of my spine which is pressing on the nerves and this sends shooting pains down my legs when i sit down or bend. MY back does not hurt if I lie down. Lately i am unable to even sit for about 10 minutes without my back hurting which is a massive problem as in school we have to sit for 50 minutes 5 times a day :/ i was given exercises to do, basic stretching, but they havn't helped and my back has increasingly got worse. I am going to go see my doctor (GP) and hope he can do something about it because at the moment im taking 800mg of pain killers twice a day.