I have experienced the same problem during flare ups. Since my Crohn's is concentrated near my terminal illium (very narrow part of intestines, extremely painful location to have CD) whenever swelling occurs there my intestines are blocked off completely and I vomit uncontrollably. One time this happened while I was our surfing and I almost drowned. I have found that the key to controlling this is to be on a strict Elimination Diet (only foods you can tolerate) along with a number of the remission-promoting herbs discussed in this forum (see other threads.) Good luck!