It does sound like Neuropathy,the first thing that come to my mind was that its common these days for young ladies to virtually starve themselves just to be thin, of course i have no idea about your neices diet but it can be a possible cause if she is lacking the B vitamins its ceratainly going to have an impact on her nerves.
I wouldn't be waiting around for to long before seeing a neuro and get all the tests up and running to find the culprit.
I hope its something thats easly fixed.
Brian