When it happens, immediately stop everything and look at what is happening, what you feel, what you are thinking or have been reading, who you are talking to or who is talking to you, etc.

How do you feel about throwing up? Have you always felt that way? What experiences have you had throwing up? I always hated throwing up and was really anxious before I started college what would happen if I had to throw up there and my mother wasn't there with the cold washcloth for my head, etc.? Of course the real experience was not like my imagined one and I did fine. But why did your unconscious pick throwing up? Does it make you less uncomfortable/anxious after you think this? I know when my husband would go out of town on business trips overnight/for a week, I would imagine bad guys breaking into the house each night so I'd have to stay awake until 3:30-4:00 when, apparently according to my unconscious, bad guys go home themselves and it would be safe to go to sleep (either take vacation time ahead of time and not go to work or lie about being "sick", etc.) or I'd spend the night at someone else's house, etc.

Obviously the chances of there being robbers, rapists, and murderers then was not any greater than other nights and, for me, it was a pretty far-fetched thing to obsess about but it did keep me from thinking of my husband being away and my being on my own, alone? It was a diversionary thought to have me obsess about something that was not likely to happen (so I was safe, just as one is safe on a roller coaster or watching a horror movie) whereas I actually did not feel safe on my own? Maybe your unconscious knows you are not going to throw up and is distracting you with that thought and managing your anxiety that way.

I finally got disgusted with being in my 40's and afraid to be on my own at night (I had lived in an apartment by myself in Washington, D.C. for 13 years before I met my husband) and I felt ashamed to have to either skip work or spend the night with someone else so I confronted the situation and came up with a "fix" that worked for me. My husband usually came to bed after I went to bed and would be in the living room watching TV or our office/porch on his computer and lights would be on. So, I kept the proper lights on at night, that didn't bother me and since the computer is quiet and far away and he'd keep the TV sound down so I could not hear it, I could just as easily pretend he was out watching TV/on his computer as that robbers were going to break in?

If I were you, I'd carry around a cheap Ziploc/Glad/Rubbermaid storage container, pack your lunch in it (each item in a plastic bag) and small roll of paper towels and call the throw up's bluff. In any event, take some action/control that acknowledges the "message" and then look for what might be causing it, where the discomfort or anxiety is coming from. Taking your unconscious seriously will get it off your case, that's all it wants, is to be "heard".