Before I figured out I had candidiasis I had that cough and congestion you're talking about. You probably know that it can be a symptom of candida overgrowth. If the doc does a nasal swab and sends it to the lab, they will tell you exactly if there's bacteria in there or not. Did you have this done? Traditionally, bacteria can only be killed by antibiotic, but it depends on what is in your lungs and sinus. What I had was a weak form of pneumonia. Pneumonia is a bacteria and a doc will Rx antibiotic, but I was able to kill it with echinacea (blood cleanser and immunity builder) and very "clean" eating... no wheat or grains, no saturated fats, no milk or milk products. All of those make mucous. Also helpful would be a liver cleanse and make sure your BMs are not backed up. Another herb is goldenseal and people say it is a natural antibiotic, though I don't know its actual properties.
Get a nose/sinus swab done by M.D. Whatever's in there is also in your lungs. (I've also had at one time a rare form of airborne staff infection) The report will tell you if there's no growth, moderate growth, or heavy growth. At this point you will have to make a judgement call about how sick you are and if you think you can wipe it out with herbs and diet. If you get into an emergency situation I would use the Antibiotic (I mean extreme emergency to keep you out of hospital) They say not to take antifungals while taking antibiotic, but it depends on the person. I've taken both at the same time and was glad I did. Hope this helps and get Well! :o) Nancy