My Son Is 10 Months Old, He Was Trying To

My son is 10 months old, he was trying to stand up, fell & hit his face hard, his nose started bleeding, I picked him up, wash his face & then checked him he was fine. The next day he had a really hard bump on his cheek, it hurts him when we touch it, its also really Hot when we touch his cheek. We took him to the ER but got told it was just a bruise. What can this be? The really hard bump inside his cheek?