I have rectal bleeding , since March 11. It seems to get heavier each day. I am very tired , a little dizzy. Went to dr , I also have my period , that comes every couple months, very cloty. I went for a ob-ultrasound. Got a call to come in and discuss the results. I m scared now. My question is . Could this be cancer? Ps. I am 50, and did have a colon op?