Al, I've been pondering this for a few days.I do every time somebody on abx has an unexpected relapse yet I never have. The obvious difference here is that you have two young children coughing and sneezing around and I don't yet after two years you should be clear of all this. What about supplements and most especially vitamin D? I took mega amounts even before I started abx and continue to this day. After all, you do live in D-deprived Scotland.
Another essential is n acetyl cysteine, to guard against reinfection. It is easy to think you are taking plenty of these every day, but checking on my husband showed that he hadn't taken any of either for more than a week and he s the one who reaised the importance of taking NAC to avois reinfection with Cpn.