Red spot in the bladder and pelvic pain.

My Urology used cystoscopy and looked inside bladder when I was complaining from having microscopic blood in the urine and I had pain in the very low part closed to the pelvic bone or under belly and usually I wake up with that pain the walking or standing helps to reduce the pain. The urology said there is red spot in my bladder but he did not know WHY. He also did biopsy for my prostate was negative but I think he did biopsy for bladder too. My question is what that reddish is in the bladder? The pain in my lower abdominal goes to many years and I get it when I put stress on the muscle of pelvic area. I have frequency of urination but not always. I am worried about Carcinoma cancer which is usually too small to detect it and I already have neuroendocrine Gastrinoma cancer primary in duodenum and spread to liver.