I am having low grade fevers everyday since hardware removal from left knee?

i had surgery on tuesday july12, 2011, everyday since then i have been having fevers from 99.4 - 100.8. i went to the ER they started me on doxycycline for acute bronchitis, but i had severe vomiting from the medicine. the blood cultures they did in the ER show no growth since sunday. the incision site doesnt look red or warm to touch and i am not coughing up any more yellow sputum, any thoughts to what is going on