First is to have a medical evaluation to try to determine what may be wrong...you speak of a herniated disk and slight scoliosis so there the problem may be or begin.
Do you do any stretching? Flexibility is key especially as the body ages. If you don't have a regular stretching routine you need to develop one and stick with it.
Have you been properly fitted? If not it is likely time you do. Your bike's current set up may not meet your bodies needs at this point in your life.
Do you do any core strength training? If not then do so...with medical support and guidance so no known injuries are aggravated.
Start all...stretching, core strength training, riding, etc....slowly and build up step by step...to rush things may cause injury and result in losing ground rather than improving.
Good luck...