I Have Been Taking A "swish And Swallow" Medication For

I have been taking a "swish and swallow" medication for thrush for the last 6 months called Nystatin. When ever I stop taking it...the thrush returns. In two weeks I am having surgery on my esophagus for a Zenker's Diverticulum. I had my pre-op CXR and it showed a number vof white wispy streaks. Could the Thrush be in my lungs, and have I developed a resistance to the Nystatin. (I'm a former nurse)