How do I know if my child had a stomach virus or influenza? He came home from school 2 days ago with a headache & loss of appetite . He also mentioned his jaw hurt. A few hours later he felt nausea & his fever spiked to 103 •F. He had chills, a severe headache, sore throat , & stomach ache. The high fever lasted all through the night. He did vomit once, but not a lot. This is now the 3rd day, he is eating a little, no more fever, & the only thing bothering him is a bad headache, a little weakness, & a scratchy throat. Also have to mention he did receive a flu shot 2 months ago. So was it influenza or a stomach virus?