Hello, My 12 Y/o Daughter Fell Backwards At School Today

Hello, my 12 y/o daughter fell backwards at school today and hit the back of her head on hard dirt surface. She did not have symptoms at the time which was at 12:00 pm. About 1 hour after incident she began to have pain in the back of her head and feels that the pain is a little worse since then, it is now 5:45 pm, she also feels dizzy and pain when she moves to a standing position, coughs or yawns. Her pupils are reactive and constrict in response to light. Could she possibly have a concussion?