why did Cole eat mouse and something like that?(such as the grasses, the insect)

Unable to move, Cole is forced to eat whatever he can in order to survive. After the attack, he initially wanted to just give up and die. When he chooses to live, he needs to eat; grass, worms, and even mice become the sustenance that keep him alive.

He's gonna get sick.

Ew, worms? I'm getting squirmy