Thanks everyone for the comments/information. Yes, it has been a long/difficult/tiring 2 years for my sister, but she's a very optimistic/happy person, so she's trying to handle it the best she can.

The 2 links are very helpful. I'll need to digest the info and speak with her about some tests that may be helpful.

Nothing immediately pops-out (she's done alot of the nerve conduction, temperature, MRI tests already, and alot of the items she doesn't have the symptoms), but we'll try to narrow things down.