When I was interviewing him earlier in the day, he had some troubles with slime and rattle in his lungs, he said, and the cold just would not let go. After the interview was over he more or less shouted "aaah, i'm tired of being sick".
But he did perform the last half of the show pretty darn good even considering the state he was in. Just unlucky.
The entire crew had been passing the bug around this tour.