Hi patJ, it frequently said by Health DepRtments, we are becoming immune to antibiotics through taking too manŷ. I've had several infections, it's called Thrombocytopenia, including breathing so was sent to see a Pulmonologist in March, he did an aspiration and yes brought out a lot of mucky stuff, which was sent off for analysis - they were looking for aspergillosi causer by moul - my housing conditions, esp in winter with damp and cold are not good. It was not thare but with no other suggestions from the pulmonologist, (analysis was o going) they haven't come up with another cause, probable or not.
The aspiration was great, left me with clear bronchial tubes, I now use an asthma type spray if I am wheezy/ oxygenless. The major cause of the mucus I don't know, but it often happens if I eat something my 'gut' doesn't like that I need to cough from the diaphragm, not my lungs. At base of oesaphagus and gullet there is a flap that opens/closes according to whether eating or breathing! So when I cough and spit out mucus I also need to blow my nose to clear that.
You knoŵ if infection is there according to colour - yellow to darker will indicate infection, white/clear should mean no infection. Urine and pooh colour can also indicate if there is problem (infection) with urinarŷ tract.
Has your Dr had a sputum test done for you? Also a test to see what antibiotics you have positive or negative responses to. I was given an antibiotic once that had no effect at all! As you say has happened in your situation.
So just some ideas for you to mull over. When looking at effects of mould spores in the air,which I had here, it was also interesting to find from my own research that many of the aerosol,s we use in the home these days are ingested through breathing, or it is absorbed by the skin. Slightly damp clothes, folded and dried on radiators or Airers in winter, don't help either! Fabrics need to drŷ out completely as single layers to prevent absorption of moisture (the cause of mould).
It might not be what you want to read/hear and may not help you - but just some food for thought as I've been through similiar experiences last year or so! I also take no meds except. thyroid one now and managed my infection by keeping my gut and digestive organs clear which has helped keep my breathing Better. I'm not medically qualified either. Research and personal intuition is what is helping me.