if it has been more than an hour, it’s in her blood stream. It is probably why she is nauseated, it’s a powerful hormone that induces her period.
It takes about 15 minutes for a pill to dissolve and start absorbing in your system. It should be through the stomach in less than an hour - depending on what else is in there. She is feeling like throwing up because of the hormones in the morning after pill. A few crackers or some dry toast might help settle her stomach.
if you can’t accept the consequences of having sex then stop doing it especially if you aren’t mature enough to handle being a parent.
How long ago did she take it? If she vomits at less than 4 hours she may need to take it again