My heart is so painful

I always steal sometime to do blogging when Hong Zheng is taking his nap in the noon. Today, after he was fall asleep, i came to PC again. An hour later he wake up. I quickly go to him so that he can sleep another one more hour. Not knowing why, he suddenly get up from his bed and accident happened! He knocked on my knee when i was about to knee down and he tumbled to his back and knocked on his head. "Pop" was the sound i heard. I was so sad and so hurt to see this happened! My heart is so painful.