Hello, 
I'm new to the group and very new to meditation.   I wanted to add a thread where people could offer explanations towards why one can have strong feelings of "sea-sickness", nausea, dizziness, and possibly even getting to the point of vomiting.  I think it is often a positive thing.  

For myself, this is simply because I forget to turn my palms down onto my legs, and sat instead with my palms up.  Having palms down lets things flow much more calmly, palms up is like diving off a diving board, backwards and into space. :)   
I hope this helps anyone going through similar.  Try things palms down.