To diagnose a urinary tract infection (UTI). Infections of the urinary tract (UTIs) are the second most common type of infection in the body. You may have a UTI if you notice: fever, tiredness or shakiness; pain or burning when you use the bathroom, urine that smells bad or looks cloudy or reddish; an urge to use the bathroom often;pressure in your lower belly; and less frequently, nausea or back pain. You must treat an Urinary tract infection with oral medication for it to go away, so it is extremely important if you suspect that you have this to be tested.