I don’t know the cause of death but I’m fairly sure it was some malignancy.
He started looking bad five years ago. AIDS? Whatever it was it was something chronic. I think he was a heavy smoker at least early on.
From memory I think he had some neuromuscular degenerative thing that affected his singing voice so he stopped singing. Then he stopped playing because of all things - believe it or not - what was essentially “tennis elbow”. He was such a pro that he said that if he could not play at the level that people expected then he wouldn’t play at all.
There may have been other issues as well - I don’t know - but those two I’m pretty sure about.