sir, i am a 22 year old male, i noticed the following symptoms since last six months.I am worried if I have colon cancer.1)A change in bowel habits, including diarrhea or constipation and a change in the consistency of the stool.2)Rectal bleeding or blood in stool.3)A feeling that bowel doesn t empty completely.Please help me regarding what i can do. Do i have colon cancer, how can i know. Where can i get a screening test done?