Doctors told woman she was too young for a colonoscopy. Then she was diagnosed with Stage 3 colon cancer / People who got colon cancer in their 20s or 30s describe what it was like and the signs that were ignored / EXCLUSIVE Tragic victims of America’s young colon cancer epidemic: From ‘healthy’ father killed at 29 to make-up artist, 35, whose stage three tumor was misdiagnosed three times