I’ve dealt with chronic prostatitis for about the last 30 years. I was diagnosed with a stricture in my urethra in my late 20s and had that opened up but still get occasional flare ups every once in a while. My symptoms are usually the sensation of sitting on walnut and/or screwed up urine flow. The doc usually prescribes an antibiotic when this happens. I’m not sure if the antibiotic is what clears things up or if the symptoms just goes away on their own.
I would even have flare ups even during times when I wasn’t riding bike.
Like some of the posters above said, make sure most of the pressure is on your sit bones. I also use a saddle with a cutout. I also try to stay hydrated.