This past week I've been feeling nauseous off and on throughout the day . It started Tuesday when I had a big ceremony to go through, at first I thought my stomach was hurting because I was hungry but then I ate and ended up throwing up my pizza later. then again on Friday I had a meeting and had a bite of pizza and instantly felt sick. but when during the week I feel nauseous for like 10 to 20 minutes then I'm fine again but it's a constant thing. I have also been experiencing diarrhea too. I had unprotected sex six days prior to my last period which started on march 31 and ended 4 days later. and my fertile days were between march 12 and march 17th. could I be pregnant or could it just be a stomach bug?