The smell of ammonia--or, more specifically, urine--is common to various conditions related to the kidneys and liver. Working with a doctor will help you narrow down the possibilities and arrive at a treatment.
As patients approach renal (kidney) failure, they may start smelling of urine. Showering will provide very temporary relief.
Kidneys normally filter nitrogenous waste compounds from the blood. However, as one approaches renal failure, these wastes don’t get removed. Eventually, they will leave through the skin–along with the tell-tale smell of urine.
Any kidney disease that causes renal failure (IgA Nephropathy, MPGN, polyscystic disease, etc.) can produce such a smell.
Something similar happens with hepatic (liver) diseases, such as hepatic encephalopathy. The liver removes many other toxins from the blood stream. If liver function is seriously reduced, an ammonia smell may result because toxins are not getting properly broken down.
The importance of getting to a doctor cannot be overemphasized. Your health is too important to play games with. If you suspect you have kidney or liver disease, call your doctor promptly.