First of all, don't let anyone tell you that because you are only 17 you can't have back problems and you are too young for any kind of spinal issues.
I also wouldn't suggest you see a chiropractor either.
Have you seen your primary doctor to see what his/her thoughts are on this?
Have you had any simple basic x-rays done on you lumbar spine?
Have you been playing a lot of sports or had any possible injury to your spine?
If you haven't seen your primary doctor, you should start there. Then I would suggest that you see a spine specialist. Either an orthopedic surgeon that specializes in spines or a neurosurgeon that specializes in spines.
Actually, at your age I would seek out a sports medicine orthopedic surgeon that specializes in spines to give you a full evaluation and determine what is going on with your back pain.
8 months of back pain is to long for you to suffer with without finding out the cause.
Good luck and let us know how things turn out.
Fran