The test done on day 3 was a rapid test for typhoid
which came positive.After 7 days widal
titre was done which shows antibody response to the infection.Though Salmonella
H is little less specific than O hence this test might need to be done again to know whether O also increases.If it dose then surely its typhoid and you need to take a proper course of antibiotics i.e 7days extra from the day fever
disappeared.So in your case maybe 10days.