Why Am I Having Pain In My Stomach Directly In

Why am I having pain in my stomach directly in the center right below/in between the rib cage? It radiates to my left side back and shoulder. I've seen a heart Dr. for low heart rate. Had stress test. It was good. Had haltermonitorfor 24 hours. Heart rate went to 39 at times. 60-70 normal range. Dr. thinks I may need a pace maker in 10-15 years but doesn't think it will benefit me yet. I had Graves disease and my thryroid was irradiated. I am on synthroid 88mcg. Dr. thought maybe low, but test says it is in normal range. I feel constipated often, but I have oatmeal almost every day and take fiber when it gets bad. I also feel gassy, and nasea with the pain. I have tried throwing up to releave the pain, but it has little results. After a while the pain goes a way for awhile. Ive missed 2 days of work because of the pain. I can't get comfortable and its kind of hard to breathe. I thought maybe thyroid, pancreatitis, or gall stones, but gall stones pain is on the right side. I had a colonoscopy about 6 months ago and I was told I won't need another for about 10 years. Could my colon be twisted or knotted or something like that? What do you think?