Boy, that was scary

We're in the kitchen eating dinner and we hear our two boys playing in the other room, nothing out of the ordinary. I always get nervous when they rough-house, but my wife says it's normal. It may be, but I still get ansy when they do this. Any way, we hear a yelp and we run into the other room and we see the big guy (Oscar) just staring at us. We turn our attention to the little guy (Kramer) and he collapses. He tried he darnedest to stand up, but he couldn't. Then he started to shake. My wife stayed with him and tried to calm him, although I wish she tried to calm me down. I got the number for the vet, put Oscar in the other room and got ready to take Kramer to the vet. Fortunately, about 1 very long minute later, he stopped shaking and stood up on his own. While his eyes looked a little glazed, he acted pretty normal. Me, on the other hand, needed a drink. He ate a treat and acted pretty normal after that. While we don't really know what happened, we think they may have bumped heads. Right now he shows no ill effects. Boy, that was scary. Here's a picture of my cutie: