What antibiotic/treatment is best for pseudomonas bacterial sinus infection?

I’ve had a bacterial sinus infection for three months now since my sinus surgery. It started shortly after the packing came out. I understand pseudomonas we very resistant in biofilm matrix form. I also have been using silver hydrosol nose spray. My rounds of anti biotics have been Levofloxacin (10day) did not eradicate bacteria. Was switched to 21 day BID Bactrim, on day 10 symptoms of worsening are occurring. What can I do/ask for? I have had a CT scan yesterday. Have yet to hear results.