Super Junior's Sungmin updated his twitter a few hours ago saying:

Will I laugh again...or will I cry too...After waking up early in the morning while I receive the sunlight, I contemplate each moment...I let out a long sigh...inhale deep breath and clench my teeth..My throat is hurting...I think that I can do better...

He seems really moody nowadays just by looking at his twitter updates and his expression during Super Junior's 3rd win on Music bank. He might be lacking in the
confidence that he need or maybe he feels sick like how he mention that his throat is hurting. He might be worried about him singing live with his throat hurting.
Well, i hope he does get better and present to us that lively and cheerful Sungmin again!

Reported by Ting18♥@ DKP
All credits to: Minie @Sujuism.blogspot.com