Case Study Frank is a 66-year-old trucker who is not your regular patient

Case Study Frank is a 66-year-old trucker who is not your regular patient. His healthcare provider is out of town, and you agree to see him for a "urinary tract infection," according to the information taken by the receptionist when Frank made the appointment. The patient described a 1-week history of painful urination and began "peeing blood last night." Frank admits that his fluid intake has decreased because "I don't want to have to pee. It hurts!" He states he has had a low-grade fever and has developed low, mid abdominal pain with palpation, radiating to his left flank in the last 24 hours. Frank's last BM was 2 days ago, and he has been "a little constipated." He cannot state whether his stream has decreased because "all I can do is think about how much it hurts to go," but it seems that he has the urge to void more frequently, including at night.

questions: Identify three differential diagnoses. Determine what is the most probable diagnosis.  (Urinary tract infections cannot be one of them). 

Provide rationale and a brief description of the pathophysiology.

 Don't let them all be related to the same body system.