Ulcerative colitis and taking asacol (mesalamine) and prednisone 2x a day still blood is coming out. My doc looks he says theres something is causing that why?

Depends. It may be that you have more severe inflammation and need escalation of medical therapy. Or occasionally allergy to Mesalamine (asacol) can cause ongoing bleeding. Or infection like c. Difficile can cause blood. See your gastroenterologist to sort this out.
Colon. Perhaps need colonoscopy to make diagnosis. Meanwhile could add probiotics like alwign and culturrelle. Eat greek style yogurt, adding blueberries- excellent antioxidant.
Surgery. When medical treatment fails or long standing disease, subtoltal or total colectomy is advisable.