Our 10 year old son seems to have the flu this week, but while I think he s had a slight fever off and on, and has been throwing up one or more times a day, he s complaining about his back hurting, in addition to head and stomach. He s got a slight cough , and has had, especially a year ago, what was diagnosed as possible gastritis . He says this feels differently--more flu-like. I m concerned that even not running a fever, his back sensitivity has gone on several days now, in addition to stomach and head ache.