My 10 year old son fell backward on concret and hit his head while running in a water play area at the park 2 days ago. Didnt see this happen and the two ladies who saw this stated it was a loud thump and they helped him up and sat him down. I took him home and gave Motrin. Has been fine until today when woke up and has been vomiting the last 2 hours. Wants to go back to sleep too. Any suggestions?