Prostate cancer

Thank you for your attention to my previous posts. My Gleason is 6. I had a consult with my urologist a few days ago and told me that there is no for surgery at this time. Will continue to monitor with PSA. But honestly, I'm scared that the cancer will spread. Lately I' m having this issue when I sit down,specially on hard surfaces. I get this light pain in my lower back, left groins and testicle. I stand up and slowly it goes away. Is this a symptom of the prostate cancer?. I would appreciate your opinions and advices. Thank you