<s>[INST] What explains dull pain on my left side, I have had a colonoscopy all is well, have had MRI of left and center abdomen they see nothing. No bowel changes, I have had polio as a child and my left side is my stronger side so I tend to favor that side since my right side is my weaker side. But it bothers me that I have this dull pain that can sometimes be intense. My Doctors don t know what the problem is and I find my self thinking about a cancer that they will find to late. I have been bothered by this for a year now all tests come out normal, what else can I do. Could it be muscular but it does not feel like a muscle ache. I m at my wits end. [/INST] Hello, thanks for using Chat Doctor. There is a vast number of causes of left abdominal pain. A negative colonoscopy and MRI is comforting as they exclude anatomical pathologies including cancer which is your worry. Cancer is associated with altered general condition, progressive weight loss, loss of appetite, weakness, sometimes low grade fevers; in the case of gut cancer, bloody stools, diarrhea or constipation, abdominal pain etc. The causes of such pain on the left side of the abdomen include diverticulitis, irritable bowel syn Chat Doctor.  </s>