Hi Dan
Welcome to ABCS.
After my 3rd TURB, which I also had Mitomycin C, I had similar problems with constant urinating every hour to 1 1/2 hours. Made it difficult to sleep at night, and driving any distant was very difficult. This lasted for about 5 weeks. I do not know what caused it maybe the mitomycin C.
I thought it was an infection, but I had that checked and no infection.
I know the pain and aggravation you are having, and I wish I had an answer for you. My Uro told me it was normal, after 3 TURBS and 12 BCG treatments for my bladder to be inflamed. I am now 16 months cancer free, so a little pain I can handle to keep cancer free.
If I were you I would have my urine checked for a bladder infection, just to be save.
I wish you all the best,
Jack