My Almost 3yr Old Tripped And Hit His Forehead On

My almost 3yr old tripped and hit his forehead on the corner of a roll cart. At first it was a knot after ice (15mins later) it looked like a donut. The center is squishy the outer ring is still hard. I took him to the ER but they sent him home said it was a bruise. He has since randomly had emotional breakdowns for no reason and just talking strange. No other symptoms.