What Causes Nausea After Losing Virginity?

Hi, my girlfriend and I lost our virginity 5 days before her period was due and used a condom. When her period was 3 days late and she was experiencing symptoms such as nausea and light headedness. She took a clearblue pregnancy test and it showed up negative after 4 days. This is now the eight day and she is feeling nauseous again along with having a light head although she flew to Miami from Ireland on holidays 2 days ago.



Should we be worried?