What happened to Luke Kuechly tonight?

Did anybody see that? He went down, they had to cart him off the field. He was sobbing, and looked like he was panting for air. His lips even looked purple. His leg looked like it got twisted but he hopped up before getting on the cart. He also went head to head with the running back and I know he has a history of concussion. Kind of scary to see the way he was acting.