Since you are already having disc prolapse since 4 years, there is a possibility of increased pressure over the nerve roots associated with compression which might be causing the problem.. Do you have any pain in lower limbs.. Any associated difficulty in walking or any tingling numbness in lower limbs.. Neck and shoulder pain may be associated with muscle spasm in lower neck or disc prolapse in cervical region as well.
Next Steps
I will suggest you to start with hot fomentation, take complete bed rest for now, take analgesic with muscle relaxant tablet, apply analgesic ointment locally, use Lumbosacral belt for support. You may need to go for a repeat MRI of Lumbosacral spine if pain is persistent. If disc problem has increased, you may require surgery..
Health Tips
Avoid heavy work, avoid sitting down, avoid Indian toilet, avoid forward bending..