I Have Discomfort In My Middle Back Area Between My

I have discomfort in my middle back area between my shoulder blades. More pronounced on my left side. I have discomfort that comes and goes in my chest in the area where my heart is. My confusion comes because I have been to a cardiologist twice in the last two years. I have had my arteries scoped with nothing found. And I have had a nuclear stress test that found no problems. I do seem to have gastric issues and sometimes have blood in my stool. My cardiologist has suggested that my chest and back pains are likely caused by gastric issues or acid reflux.