Your wife may be going through her menopause but a pain under the ribs on the right side of the abdomen is unusual for a period pain. Pain from biliary colic (gallstones) can be in this area and is very severe; it comes on and off very suddenly. It may last a few hours and then a dull ache may remain for a short while. It usually has no pattern and can come on at any time. However the episodes are usually very circumscribed and it would be unusual for it to come and go for 12 hours as in your wife's case. A burning pain can originate from anywhere but is often related to reflux/acid into the gullet.
I see that she has a urinary calculus - but again the pain is a bit high up for this to be the cause.
I think you should be reassured that if all her tests are negative (you haven't told us what they are) and if she is not losing weight, then the pain cannot be due to a serious cause. Hopefully it will settle in time.