I have had reoccuring sinus infections that clearup on meds. i am currently on a course of levaquin, (levofloxacin) and it's back. why is this? it's a bad one.

Recurrent sinusitis : This is a complex issue . It could keep coming back if you received antibiotics that didn't cover resistant bacteria, maybe you didn't get other adjunctive rx in addition to antibiotics like steroids, or there is a chronic inflammation that is interfering with sinus drainage. You may have sinus anatomy problems, deviated septum, and other issues. See an ENT for full exam and work-up.