Sciatic nerve. She should go see a chiro. I've dealt with a little lower back pain before, but never nerve damage. But it sounds like how people have described sciatica.
She went in and it was worse than I thiught it'd be: adverse reaction to a flu shot! She can't walk without help and in pretty much constant pain without the hydrocodone. Silver lining: you don't have to worry about nerve damage from a disc issue - the vaccine should leave the system in 19 days. Scary stuff.
Weird. I had no idea that a person could get back pain as a result from a flu shot. Its a good thing it isn't a nerve issue.