Two weeks ago, my low back was damaged by heavy weight lifting. and after MRI, the result is as follow: 1) large size posterior central disc protrusion with moderate thecal sac compression is seen at L5-S1 level. 2) posterior disc bulging is also seen at L4-L5 level. dear Doctors, i don't feel any pain or numbness on my feet. just when i walk, sit or bend, i feel pain in the lower part of my back. also after doing physiotherapy the pain have reduced. is the surgery need? thanks