Update

Came back from the hospital just now with rather good news. My dad passed most of the medical tests including an echocardiogram. However, a couple hours ago we just found out that the root of the problem may be a form of infection from tuberculosis that attacks the kidneys, thus accounting for the fever and other symptoms.

Not untreatable, but it may mean a longer stay in the medical centre. It's the doctor's opinion that he may have gotten infected by a patient during work. Currently reading what I can on the subject.

More updates as soon as I get them. Thanks for your support, folks.