thanks to HCM I can understand your father concern with above complaints I came to know he is suffering from congestive heart failure. plz try to keep sugar in control .. he has to use higher antibiotic like augmentin or meropenum daily for 7 days for amputation of leg . this same antibiotic will control the infection lungs also load on heart will be reduced by diuretics like Lasix .. this will improve the heart function and he nay not feel discomfort .ok he need daily or alternate dressing of wound ,if not healing need to send culture of that discharge for lab. ok don t worry take care of his lung and heart with proper usage of prescribed medicine ny your cardiologist ok ..