"He gave it his all," added Alfredo. "But health always comes first. Proud of him for even getting out there and giving it a go. Today was a rough one."
The star's manager Scooter Braun also defended his charge, writing: "He tried his hardest, you guys don't see him in between songs when he comes offstage, I do, I don't know how he made it as far as he did.
"He's going to be OK... kid is tougher then anyone..."