According to the Admin of gyuhyun.cn
today Super Junior M started filming a show at 8 PM.
They think that Kyuhyun is sick due to heatstroke
as the weather is really bad where they are right now
and because the studio where they filmed was very crowded.
Kyuhyun vomited on stage and kept resting on Siwon,
or "leaning on him for support" as she put it.
He left the stage for 25 minutes and then went back to filming.
Filming ended at midnight.
Original source. gyuhyun.cn
Thank you very much to melon; for translating this for me.
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If you watched his monologue, you should know he's pushing himself harder and harder because he wants to be on stage, because he wants to do what he was born to do and what he likes, because he does not want to disappoint and simply because he's Cho Kyuhyun. And Cho Kyuhyun always tries to do and does his best. Kyuhyun hasn't got all the rest he was supposed to get and I'm surprised he's travelling so much, dancing and participating in all these shows. On Monday they flew from Seoul to Beijing, on Tuesday to Changsha, today to Guangzhou and Nanchang and on May 4th back to Beijing for an interview with sina and they have more activities between the 6th and 10th in Wuhan and Changsha. That's it.