[Kindred]

I don't think (from a quick google search) that nausea and vomiting start so soon in pregnancy- 2-3 weeks is the earliest but around 6 seems to be the average, so have you been sexually active that long? It's also important to note there are so many other things that could be making her feel ill, and I wouldn't jump to pregnancy being the first cause of sickness if you're having protected sex. Headache and fever indicate a viral infection coupled with nausea.