I'm 23, and I had my Chiari surgery on December 1, 2011. I had a very similar experience post-op. At around the 5 week mark I felt extremely weak and tired all the time, i was shaking alot and could barely hold a glass of water without dropping it. The feelings had passed after a while of feeling that way. But for me I ended up having a swelling problem come directly after that time. unless told otherwise from your daughter's doctors I dont think you have anything to worry about. just make sure that she eats well and try to lift her spirits - ive been having some depression since the surgery and most of the time mental status has a huge effect on how you heal.