I recently had a similar situation with my rescue ridgeback hound.
She was obsessing on keeping her genital area clean and would lick the area almost constantly. ALso she had a somewhat strong amonia type body odor. I took her to the vet and found -by xray- she had 9 bladder stones, each about 1/2 inch in diameter. Surgery removed them and she has fully recovered. The amonia smell would not be present in every case but I have had several dogs who have developed this condition and surgery has been needed in every case. A modification in diet and / or the addition of medication can keep this situation from reoccurring. I have a 6 pound toy poodle who had stones removed at 2 AM in emergency surgery11 years ago and she has been on a daily suppliment of Methoform (1/2 500 mg tablet) and I have her xrayed every two years no redevelopment.
Xrays are the cheapest way to eleminate a host of problems.