My father's doctor did a CT scan, to check for abnormalities in the brain, and electrocardiograms to check for abnormailities in heart. This doctor gave my father "a clean bill of health", Since then he suffered two strokes and a heart attack. new doctors found evidence of serious medical conditions which triggered the strokes and heart attack, and which could have been treated if detected on time. his regular doctor now says that the scan was unclear. Shouldn't he have done the test again? what recourse we have?

If medical experts concur that your father's present health problems were avoidable, and should have been prevented under the governing standard of care, he may well have a viable malpractice case.