Adult dog shivers and eats carpet when i leave

Hello there,

I adopted an adult shi tzu last summer and he was always fine being on his own while i gone to work, never chewed on anything, never did anything wrong, slept the whole time. Last week, he started to shiver when i took my purse to go to work. He did that all week, and then on Friday, when i came back home after work, he had chewed up a HUGE chunk of my carpet! He has many toys that he doesnt seem to touch while i'm gone including a kong full of treats that he only starts eating when i come back home after work. I also take him for a 30 min walk in the morning before leaving and 2 more walks in the evening. I dont know what's happening? Nothing has changed in our every day lives, i dont get it. Why does he shiver like that when i leave, makes me so sad to see him like that but i dont know what to do or why he does it. Any ideas/suggestions? THANKS!!!!