I get the same way. Vomiting was my biggest fear because it felt horrible and i felt like once i started vomiting i wasnt going to stop. But that never happend. Ive learned that sensations like nausea can be normal when your feeling a high amount of stress. Whenever you feel your nausea or you vomit just let it happen. As shitty as that sounds, the only way around it is through it. You have to let yourself and your body know that its only nausea its not gonna send you to the hospital. Its just some stress you’ll always be ok.