I had the same experience for 5 years, and I took, on different occasions, Levaquin, a Z-pack, and Augmentin. Awesome antiobiotics indeed, they killed every pathogen in my body except several in my sinuses, which grew back immediately.
According to Mayo Clinic research, sinus infections don't follow the regular model of tissue infection. I've borne out that research with a sinus flush that washes out the infected mucus, and I am on my 5th year of clear sinuses.