There is a link that will show You some of the early signs of pregnancy although it is different for every individual. Some woman do not experience anything until much later while some experience all of them.
http://www.womens-health-questions.com/pregnancysymptoms.html
The most obvious though is "Missed period".
completely agreed to clysta...
Sex shouldn't cause vomiting. In some women it might cause nausea or vomiting because of the hormone and adrenaline rush, but to my understanding this isn't typical. Symptoms from pregnancy don't occur until after implantation has occurred. This is generally 6-14 days after ovulation and the sexual encounter. Symptoms very with each female and some never have any. While they may be useful in detecting pregnancy, they are also very unreliable as many dozens of things cause them.