Radiation proctitis and radiation cystitis can be side-effects of SBRT. Often they don't show up at all; sometimes they emerge shortly after therapy, and sometimes they show up years later; sometimes they go away quickly on their own, and sometimes they don't. They can both be confirmed with imaging (a routine colonoscopy can see the proctitis, while a cystoscopy can see the cystitis: they both show up as angry, inflamed areas on the monitor).

There are treatments if it becomes unbearable, but if you can live with it without too much discomfort, I suggest letting it be and crossing your fingers that it just goes away. I, unfortunately, seem to have both for the long haul, but they don't bother me that often, so I haven't asked for anything like hyperbariatric treatment (pumping my bladder full of pure oxygen every day for weeks to promote healing); instead, I just go easy on the caffeine and stay hydrated. If I have a spicy meal, I know in advance that I'm going to be feeling it in both areas. I've seen specialists for both (proctologist and urological oncologist), and they've confirmed that it's not "cancer-involved", just another little thing to deal with.