I have also had spinal trauma, a botched operation and suffer from Chronic pain. People with spinal injuries have a much higher occurrence of gallstones. It is thought that this may be caused by an interruption of a major nerve that controls the gallbladder. However, the medication and pain killers are also responsible. The drug Amitriptyline is often prescribed to increase the pain threshold and help sleep but unfortunately it stalls stomach emptying and foods lies in the stomach overnight. The long term result of this is that the normal housekeeping process don't keep the gallbladder clean and Gallstones or biliary sludge can develop. However, you may just have developed Gallstones in common with may people because of life-style stresses.
I have had great success in using alternative treatments and a programme of Liver Flushes gave the greatest improvement to my health.