Unfortunately, i feel your pain! I have had the same symptoms as you for years now, and took some of the same medication, with very view results. Have you had an MRI or bone scan? The pain I was dealing with ended up not being from my scoliosis. It was due to a few herniated discs and a bulging disc that was pushing on my S1 nerve, causing the shooting down the leg pain. Prescriptions usually dont fix that pain. This summer I'll be meeting with a neuro surgeon to discuss the surgery to fix the bulging disc. For your long car trip, I'd tell your doctor your issue and maybe he can give you some great pointers. When I'm suffering from the pain I use those stick on extra strength icy hot patches. They don't always do the trick, but they relax me a little bit. A foam pillow or one of those curved neck pillows made for the car/airplane may help also. If I think of anything else I'll let you know!
19 years old College Soph
Diagnosed: 6th grade (can't remember curve degrees)
Boston Brace 2000-2002, 23/7...
Curves reside at 35T and 33L
Aug 2002: Osteoid Osteoma (tumor) removed from L3
Jan 26.. diagnosed with slow progressing DDD and sacroiliitis.. get fitted for my new SI Belt on the 31st