My 6 year old grandson has had high fever, chills, vomiting for 5 days now.  ER did chest X-ray, flu swab, WBC, UA, all negative, WBC only 4 pts above normal.  Diagnosed with virus, directed to go home and treat fever, he is still sick with no improvement.  Could a virus last this long?
It indeed seems like a viral infection and your doctor is right about it. A viral infection often lasts for 5-10 days and does not show up on the blood tests or X-ray. The virus could indeed last that long and may be more. Please be patient as it may take some time for him to recover. Antibiotics are not likely to help. However, if the fever lasts for more than 7-10 days, you may visit the doctor again and get the child tested for typhoid which could be another probable cause.