So sorry to hear about your issues. You have really been through a LOT! When you mention "chemo" after a TURB I assume you mean that they did a wash with mitomycin after? And you had an allergic reaction to it?
What type of treatments did you have when your cancer recurred (I assume that this is why so many TURBs?) Did you ever have BCG? Often that is the treatment when bladder cancer recurs. It IS unusual to have so many TURBs...usually a decision is made to try something different long before that. I do think it is good that you finally got a second opinion and Mayo does have a good reputation.
However, if you are not comfortable with your new urologist NOW is the time to make a change, particularly since you are facing radical cystectomy. This is MAJOR surgery and you will need all the support you can get. You do need a urologist who does many many of these, particularly in women. But you do need to have confidence in him. It is possible that he did not feel comfortable prescribing an aniti-yeast drug because of your reactions to mitomycin and thought that your gyno might be more familiar with your history? It would be a good idea to talk with your new urologist and ask him these questions. If he is not open to the discussion with you, then you know it is time to move.
Bladder cancer is treated somewhat differently than many other cancers and the "gold standard" when it keeps returning is to remove the bladder. Often chemotherapy is used either before or after the surgery, so an oncologist works along with the urologist, but chemo alone is not sufficient.
Right now you need to get answers to your concerns. If you do decide to move your care, Dr. Gary Steinberg at the University of Chicago and Dr Michael O'Donnell at the University of Iowa have excellent reputations. The most important consideration now is saving your life, and bladder removal, if necessary, can do this.
Wishing you all the bests
Sara Anne