Bad luck, most likely. Sounds like a first got flu, which then progressed into pneumonia. This is normal. Then he was admitted to the hospital, and probably c

Bad luck, most likely. Sounds like a first got flu, which then progressed into pneumonia. This is normal. Then he was admitted to the hospital, and probably contracted MRSA - which is not unusual either. Or did he get it prior to that? Either way, it happens. And from there it progressed into sepsis, which he might have been fighting for some time? Anyway, heart attacks, strokes, etc. can happen when you get sepsis. Sepsis can come out of nowhere. Doesn't really sound suspicious or sudden.