The key details are found in DOD Inst. 6130.03 This is the document that defines all the disqualifying conditions and you should become very familiar with it if you want to appeal or contest a waiver denial. Often, the disqualifier is a "history of" something, even if that condition was resolved a long time ago. Sometimes there is a timeline like 12 months or 5 years, other times a 'history of' will be a DQ no matter how long ago it was.
https://www.med.navy.mil/sites/nmotc/nami/arwg/Documents/WaiverGuide/DODI_6130.03_JUL12.pdf
For kidney stones, this is what is says are disqualifying conditions:
Urolithiasis if any of the following apply:
(1) Current stone of 3 mm or greater.
(2) Current multiple stones of any size.
(3) History of symptomatic urolithiasis within the preceding 12 months.
(4) History of nephrocalcinosis, bilateral renal calculi, or recurrent urolithiasis at any time.
(5) History of urolithiasis requiring a procedure
The problem with 'history of' issues, is not that you need to show that you are healthy now. Rather, you need to somehow show strong evidence that you are very unlikely to have a recurrence in the future. It might be worthwhile to talk to you doctor and see if there is any further info or documentation or testing that can be provided that could help make your case. Usually, DODMERB and the waiver authority is happy to consider any new information you might have. But if all you are doing is re-stating what they've already seen you're not likely to get a different decision.
It's getting very late and it's possible that your spot could be assigned to someone on the waiting list soon, so if you think you have additional info you should gather and send it asap.
best of luck!