Vomiting can happen when you are pregnant, but not all vomiting is caused by pregnancy, so you can determine this by testing if possible. For example, you can buy a pregnancy test about 12 days after intercourse to rule out the possibility of conception, which is very accurate at this time. You can also take a blood test for HCG, which can be done about 8-10 days after intercourse, to rule out the possibility of conception. If there is no pregnancy, this time is due to gastrointestinal disorders caused by stomach regurgitation, also due to improper diet caused by gastrointestinal disorders, this time to small meals. If necessary, you can also go to the hospital to register gastroenterology, to rule out any abnormality, according to the situation can also use drugs to regulate.