Hi Eve,
thing is that not every symptom has a certain meaning, but a symptom can have different mechanisms to create it. In the wiki we find differential diagnoses for other tissues that can create a similar reaction. Also the compass is a good help to differentiate tissue and brain layers (like "the more feeling, the more new brain")
Try searching for "nausea" in the book, there are a couple of different organ examples coming up. Usually it gets pretty clear for the individual which of these are worth to explore.