Hello. Welcome to HCM.
you have not mentioned your age.... considering you having pain for last 15 years, it is probably degenerative disc disease- which includes disc prolapse
, bulge as well as lumbar canal stenosis. Best approach for you will be to visit a neurologist
. Some minor physical tests and investigations will reveal the exact situation. Thereafter, you can go in for physiotherapy
or minor surgical procedures whichever is best.