I have a very big problem that has been dragging me on for quite a long time. Every time I am under some kind of pressure I throw up. Meaning that every time my heart starts beating something goes on in my stomach and I can't handle throwing up no matter where I find myself. If I have an interview I have to go there starving otherwise I will throw up. Or if Im in a date I can't go for dinner. Im tired going to the movies always. I need help. Im 20yrs old and smoke about 5 cigarettes a day. Drink alcohol occasionally, about 2 or 3 times a month.
I would really appreciate if anyone has an advice.
Thank you.

You could have any number of problems.
You need to go get a diagnosis and let us know. Then we can give you some ideas on things you can try doing to help.

I'm no health professional, but it sounds like you may have anxiety problems. Though I agree with the advice above that it may be a number of issues. Have you spoken to a doctor about it? If not, I advise you do.