Hi. The PA In My Doctor's Office Ordered Doxycycline For

Hi. The PA in my doctor's office ordered Doxycycline for my bad sinus infection 4 days ago. As of today I have no improvement at all, in fact I'm worse. Then today I happened to look up doxycycline and found that it's specifically for bladder infections and acne! My question is, have you ever seen sinus infections helped from Doxycycline? What medications are most effective? (And, please excuse the spelling error!)
Mrs. Lambert