There are a number of arguments about what can cause problems from drinking wine, for example some say it could be to Sulphur dioxide which is the preservative often used in wine and on its own is quite nasty stuff - usually put in as sodium metabisulphite or Campden tablets, others argue it can be the finings used.... see
http://homewinery.info/blog/?p=108 for a discussion on some of the suspects - as you will see not everybody agrees as usual, but if she is suffering the answer may well be in here!