What are symptoms for a stomach virus i think i have one my stomach has been upset like im sick for 3 weeks then it went away and now it's back?

Many: There are many symptoms of a stomach virus, including nausea, vomiting, feeling tired or weak, but these are also signs of pregnancy. With a stomach virus, you may have fever & diarrhea as well, but not always. If you're sexually active you should check a home pregnancy test. Either way, if the symptoms have been going on this long, you should see a doctor as well.