You can have symptoms of UTI without having a bladder infection. This can sometimes be due to spasms in the pelvic floor muscles, or sometimes because the bladder muscle becomes hyperactive. PLease encourage your mom to get evaluated by a urogynecologist to rule out other causes of her symptoms, like bladder tumors, or other pelvic masses. Then the physician can offer an appropriate therapy to address either the muscle spasms, or the overactive bladder.