I’m sorry to hear about your struggles but I would like to assure you that this is actually quite common after oral cancer treatment. I have suffered through the same sequence of events for many years now. I was diagnosed 18 years ago and am 16 years post treatment. I flip flopped from bacterial infections and Candida. Fortunately my docs give me a prescription for continuous Fluconazole and Clotrimazole troches as well as Nystatin. After so many occurrences I know when it’s time to start anti-fungals. They do alleviate the infection, but sorry to say, in my experience it’s a non-ending cycle. Hang in there.