I had similar issues that originally developed from colo-rectal surgery years ago, so was already on a daily docusate-calcium stool softener coming into the PCa world. It inflicts a constant state of multiple BMs per day, but when I stop it, the bleeding starts within a day. The colo-rectal guy says keep using it. I also use a cream that is similar to the protofoam (analphram) if things get bad. Before RT, I could stop both for days or even months without issue. Not so any more.
As always, be sure all the appropriate docs are aware of the issue. My GP has me keep a round of antibiotics on hand, to be used if the bleeding persists. Generally I throw them away and get a new batch every year, but some have been used.
Mt radiation cystitis kicked in 18 months after the end of RT (almost to the day), and is constant now.