My 4 year old slipped getting into the shower. He slammed the left side of his head on the bath tub floor (above the left ear). He screamed a lot and instantly had an very sizable lump (hard). He wad already exhausted after attending gymnastics class. We kept him up for a couple of hours, but then he fell asleep. What should I do? Wake home through the night? Should I wake him now and take him to the ER? He was acting fine and his pupils were normal. He just has an enormous hard lump that is concerning as well as knowing how it happened ( slip in the shower). Any advice is so greatly appreciated!