What Causes Brown Vaginal Discharge Along With Nausea And Dizziness?

Hey, my gorlfriends period was a few days early, and we engaged in sexual intercourse the day after it ended. We did not use a condom initially, but stopped before anything happened on my end and did not have further intercourse. Since then, she has had brown vaginal discharge, nausea, and dizzyness but not at the same time. What could this be?