Chances I Have Colon Or Stomach Cancer

About 5 months ago I noticed I was starting to have blood (bright red) mixed in with each bowl movement. It progressed from there to looser stools with mucus and blood. For the past 4 months, I have been passing loose stools only, and mostly just bright red blood and lots of it. I have pain and tenderness in my mid abdomen, and notice pain also in my lower abdomen. I went in for a CT scan with contrast which she found "pockets" she said, and the doctor did a blood test in which she said my iron was an 8 and started me on daily iron for anemia.

I was scheduled for a colonoscopy and the other one where they look in your stomach but my insurance is refusing to approve the tests. I also forgot to mention that I have had digestion problems for about the past 3 years progressing from mild to severe GERD which I treat mostly by taking around 800-1000 mg of over the counter cemetidine.

I'm still feeling quite bad, fatigued, and much pain in abdomen for short periods in which I pass blood and very small amounts of dark brown green loose stool.

My question is would the blood/CT test have shown any cancer growth alone, and or should I go in to the emergency room to get the other tests. I have been modifying my daily diet to fresh carrot/broccoli/beet juice along with a product called Vega which I only started a few days ago. I'm 43 about 5'10" and weigh around 240...Yep I like to eat, but know I need to stick on the modified diet at least until I drop all that extra weight.

And for the good doctor, what are the chances I have some kind of colon/stomach cancer?

Thank you very much.