This are parts of pregnancy symptoms that may cause someone to feel that although they should eat as that is what the baby is depending on as well for nutrition. So if she is not eating she should go to the doctor and get checked immediately and see what could be causing this. 6 months is deep in the pregnancy and such ailments should be attended to immediately to avoid problems in the near future.
With my first 2 kids I threw up A LOT. In fact one of the secretaries at my job said she never saw anyone that looked green due to nausea until i was pregnant. For some, this is just part of pregnancy. Thankfully I was able to get through another pregnancy with almost no nausea!