What Causes Fever With Chills And Vomiting After Injury?

i just had lower back surgery and i am bruised across my whole back. i got the procedure done on the 8th and have been runimng a high fever with the chilles and shaking raelly bad.. had to go to the er on sat. the 13th . my temp. was 102.7 and i vomitted once really bad when they were putting in the iv.. they checked for flu and said i wqas negative but would not tell me why i had a bad fever nor would they say anything when i asked about staph..what do yuo think doc...my temp is 102.1 right now