Have you considered the infection is fungal?

For people that have had long term Antibiotic treatment, the cause of sinus pain is fungal and not bacterial.

Have you being tested for fungal infection?

ALso, are you eating dairy?

Dairy produces more mucus and congestion.

I would recommend to stop dairy products, begin a high doses of Vitamin C regimen and try to find out if you need to follow anti-candida protocol.

Also read information about the nasal irrigators and the use ACV (apple cidar vinegar).

I hope you feel better soon.

Blessings
Zule