I had the same cancer and treatment but mine was Stage 3b in 2009. A few tears later I had a stage 1 sessile polyp removed from my rectum which caused some loss of sphincter control. So I deal with some incontinence issues and have to be careful. I also have tissue shedding. They call is friable tissue I think. I have had several UTI’s also. I am 66. My life is completely controlled by my bowels.
I had a bladder repair surgery several years ago and the surgeon told be to be careful about not allowing my bowels to back up because of the way they lay across my ureters. If they get too heavy they block off the flow out of my kidneys. This gets painful but also causes me painful bladder spasms that feel like an infection but it isn’t. So be careful slowing down your bowels. I don’t use Imodium for that reason. On top of that, I was diagnosed with gastroparesis a couple years ago so I am fearful of Immodium making it worse. Its hard to live with all these things. I feel your struggle.