Smell of old urine

Hi, welcome to the ehealth forum and I am glad to help you.
You seem concerned with the urine odor. Urine odor varies. However, if you drink enough fluids and are otherwise healthy, urine does not usually have a strong smell. Changes in urine odor are usually temporary. Such changes are not always a sign of disease. Certain foods and medicines, including vitamins, may affect your urine's odor. For example, asparagus causes a characteristic urine odor.
However, foul smelling urine may be due to bacteria, such as that responsible for urinary tract infections. Liver disease and certain metabolic disorders may cause musty smelling urine. Abnormal urine odor may indicate dehydration, hepatic (liver) failure, ketonuria, urinary tract infection (UTI).
You must consult your doctor and get urine culture and urinalysis tests done to properly diagnose the problem as the same cannot made online.
Hope this helps. Take care.
Note: This post is not to emphasise final diagnosis as the same cannot be made online and is aimed just to provide medical information and no treatment suggested above be taken without face to face consultation with health care professional.