Help with vomiting from severe anxiety

Exactly what the topic says, I need help. When I get extremely nervous or anxious i get violently sick. It doesn't happen often-it's only happened four times in these two years. First two times was when I had funerals to go to, I threw up about three times before each and then once during it. The last two times were on really important dates, one of which I threw up right in the middle of. I have a date to go rock climbing (I rock climb at a gym regularly and we're going outside for my 1st time) and I've been feeling anxiety queasiness for the days up to the date. I'm really worried about throwing up before we begin climbing tomorrow and not being able to climb. Does anyone else experience this, and if so, what helps you? I'm going to take a warm bath tonight but I'll take any ideas.