What Are The Symptoms Of Concussion?

My 10 year old son son was hit in his left temple with a plastic outdoor disc hockey puck. I gave him ice and 2 tablespoons of Motrin right away. His temple does have a bump on it. It hurts to chew and lights are a bit blurry but regular lights are too bright. What are some signs that I need to look at to determine if Imhave to take him to an emergency room?