Hi, my wife a 71 year old female about 5ft
If your primary physician isn't able to isolate the cause, I'd consider consulting a surgeon.
Besides cracked/inflammed ribs, other causes to consider include gastritis, pancreatitis, lung inflammation and kidney stone. Chest xray would have revealed signs of lung inflammation if any. Since that was normal, I'd would want to rule out other conditions. Therefore if your primary physician isn't able to help you, consider consulting a general surgeon. An ultrasound scan may be performed.
Hope this helps. Let me know if you need clarifications.