Have been having this upper left rib pain, right at ribcage, and upper left back on and off for a year or so. recently did an xray and everything was normal. if it was cancer would it show? worried about cancer?

Cancer that has spread to the ribs world sometime show up on a plain x-ray. A nuclear medicine, bone scan, and pet scan are usually used to diagnose cancer spread to the ribs. I do not know what your risk factors are cancer . This is unusual at age 31, ask your primary care physician if they think further studies are indicated.

Would not likely cancer. I would move to a diet that is likely to reduce your risk or cancer such as the DASH Diet.