Re: Back injury pre-existing?
Welcome to the board. I am sorry you are having further difficulties.
I can give you some general information, but can't really comment on your situation since I don't know the particulars.
It is possible to have sciatic pain change legs. What may have happened is that you had disc bulges back in 2007 which healed. Now several years later the same discs have bulged but the weakness is in a slightly different location. Depending on where the disc bulges, it can push out to the left or right of center, or the bulge can happen right in the middle or central location.
When there is a bulge in the middle it can cause pain in both legs or it can even switch back and forth. This can also be a sign of an instability.
I don't know much about the workings of Workman's Comp but I can see how if someone injured one or more discs at one point, and several years later the same discs begin to have issues again, it would be fairly easy to say it is the same injury.
Whenever someone has a disc problem that heals, there will always be a weakness in that disc. If the same disc bulges in a different area of the disc, is that a new "injury" or does it bulge again because it was already weaker due to the first assault? I don't know the answer to that.