Try to stay as gently mobile as you can and try using ice on the affected area. As things have not been improving for you, you may want to go back and see your doctor so they can re-examine you and advise you on an appropriate course of action. This might involve referral to someone like a chiropractor for treatment and advice.
When you say your doctors "looked at me" do you mean they ran test? Have you had an MRI on your back? If not, I would ask the doctor to refer you to a rheumatologist. Nobody is "too young" for back pain. I have read about juvenile arthritis and other diseases; you should get an MRI. You might have injured a couple of disc. Be persistent with your doctors - they see a lot and sometimes just blow things off when they should look more seriously. They have a difficult job and make mistakes just like the rest of us.
Good luck.