I assume you're smoking it?
By consuming marijuana you might very well be treating your symptoms but not your condition(s). You need to consider that the use of cannabis isn't approved for any disease or condition, for several reasons: 1) evidence to support its use for the treatment of a very limited number of conditions is shaky at best, 2) you don't know the exact source or purification method for the cannabis you're using so you don't know what harmful chemicals it might contain, 3) smoking has further potentially damaging health effects, and 4) there is a risk of abuse.
You're still an adolescent so you have more options to treat your scoliosis than if you were an adult. Have you discussed surgery and bracing options with your physician?
How physically active are you? Increasing the anount of exercise you get could help relieve the pain you're feeling in your back and legs (weakness from inactivity is a common cause).