Hi,
I too have a VP shunt and get blackening out when i arise, lately its been getting worse.

In september, my opthamologist found that i had papilledema behind my right eye, which indicated intercranial pressure.
CT scans were exactly the same as they had always been, and they didnt suggest any problems with my shunt.
I had an icp monitor fitted 2 days later and then that night I showed very bad symptoms of shunt malfunction.
Vomitting constantly for hours.
Irritatability
A very nasty headache
Sore eyes
...I soon went into a comatose state, where i could not respond to anything...i was rushed down for an emergency CT scan. Still nothing at all showed up.
I was taken into an emergency shunt revision very shortly after where a nurse whitnessed the fluid fly across the theatre due to such high pressure.

12 years ago, exactly the same thing happened, Scans and tests showed up with no abnormalities until my shunt malfunctioned and put me in such a bad state, revision was adament.

I suggest you ask your NS about the possibility of having an ICP monitor inserted for a few days to measure the pressure in the head, this gives an accurate reading. =)

good luck to you and your daughter x