I'm glad that you had a physical exam to rule out any medical issue that could be causing digestive problems. I agree that it does sound like this is more of a psychological issue- and to me, it sounds like you've developed a phobia of vomiting.
Phobias of all kinds are fairly common and usually require the help of a psychologist. I would suggest that you find a psychologist near you who specializes in treating phobias and that you briefly tell him/her what your fear is when you make the appointment so that she/he can begin to develop a treatment plan for you. The psychologist will likely spend the first meeting taking a complete history, including (but not limited to) your experiences with throwing up. After that, you and the therapist will develop a treatment plan-- usually with phobias this involves some kind of either Imaginal or In Vivo Exposure Therapy. You can do some searching online to learn more about these therapies, but the idea behind them is that you gradually expose yourself to the thing that you are afraid of and, at the same time, learn skills to manage the anxiety that comes up with exposure. Eventually, with practice, the fear goes away as you have had more exposure to the feared thing (throwing up) and see that nothing really terrible happens.
You could try to do some of the Exposure therapy that I mentioned earlier on your own. This is challenging, but if you're very committed you could give it a try. You would need to do some research online about how to do this- I would recommend that you buy one of the Phobia workbooks (the ones by Edna Foa are really good) so that you would have a program to follow at home.
Also, it is probably worth your while to talk to a few psychologists- many therapists offer sliding scale fees that can start as low as $20 per hour.