There is no doubt in my mind that what you are experiencing is a combination of IBS and horrible anxiety. The reason this is happening to you is because your body is literally tricking you into thinking that you are ill. Tests have been ordered and nothing has been found, and I know exactly how you feel. I have been experiencing debilitating abdominal pain for almost 3 years now and I have had x-rays, blood work, physical examinations, etc. and nothing has been found.
I am still experiencing this pain, but I have given up trying to find an answer and just take it for what it is. Your suicidal thoughts need to be addressed as well. While you may feel hopeless, I know you DO NOT have colon cancer.