I've been fighting sinus infections for nearly 2 years and haven't found the answer yet. I've been on Amoxicillin, Augmentin, Bactrim, Diflucan, Cleocin, Bactroban spray I had to mix up myself, saline sprays and rinses, my own saline and baby shampoo sinus rinse (using a tiny teapot like a "Netti"). I use Flonase spray to try to shrink the nasal membranes. OTC I've also used menthol spray, Vick's Vapo Rub, and Mucinex.
I've had X-rays and CTs, the latter showing infection. It all started with an accident and broken nose causing more deviated septum than I had before. I think the openings of some of the sinuses are shut.
Beware of using antihistamines. They can just dry out the tissues and cause even worse infection. Ask your ENT first! Mucinex 12 hour does help. It liquifies the secretions so the cilia in the sinuses can clear them and they can drain.
I suspect I've developped a resistant "bacterial plaque" which my allergist was trying to kill off with the Bactroban mix I use as a spray. I just don't think it's getting where it needs to go. Diflucan for fungus and yeast seemed to help at first, but isn't doing anything now.
Today is a pretty bad day. Maxillary sinuses are worse than usual, causing hot, red mask like a raccoon across cheeks and nose. A couple of aspirin eases that - reduces swelling, pain and fever. I am trying to get back in to see the ENT, but it takes 2 weeks to get an appointment. (I've asked for any cancellation.) I nearly went to ER last night because of the pain. Fortunately I have a bunch of stuff for my degenerating spine and slipping ribs, which on top of my fibro tramadol, is keeping me at a tolerable level.