I am having severe pain of the nerve starting from lower back to the toe. It has started two months back when I has stomach upset.When I was vomiting I suddenly sat down on the floor and when I tried to get up I couldn't becoz of the severe back pain.I had to tk bed rest and care for a month. And the pain comes up again when I travel for more than an hour in bus or stand still for some time. And the pain triggers when I sneeze too. What could be the reason?i don't feel pain when on pain killers.