I also have nausea from time to time. But I know when I have nausea. I have noticed that it seems to come along with stress. I think the nausea that comes along with a BT is severe and often induces vomiting. You cannot assess every feeling you get, particularly with a BT fear. Because your brain controls your entire body, Google will tell you every twinge , sensation and feeling is a BT. It is not.
When I was at the height of my BT fear (still have the fear! btw), I didn't have much of an appetite because I was so worried and anxious about it.