Suggest Treatment For Severe Sinus Infection

Have had what appeared to be sinus infection, 2 or more close together. Currently have increased coughing and what appears to be sinus drainage. Have been on Levaquin, 1 per day for a 21 day period. Have not finished the 21 days but the coughing and sinus issue appears to have gotten worse. Why the dastic means to order a CT scan of head / sinuses?