Ammonia smell in urine could be due to bacterial infection in the urinary tract without regular symptoms of UTI, dehydration, consumption of red meat or high protein foods.
I think you should consult your doctor and get the urine examined for infection, ketones etc.
You may also need to get a urine culture done. Frequent urination can also be due to urine infection or kindey conditions and diabetes. Your blood sugar levels also need to be checked. Hope this helps.