What Causes Vomiting And Diarrhea In A Child After Falling Down?

hi there. I read a question where somebody asked could her toddler have concussion because he is vommitting and has diarhea. I saw a doctor answered no its food poisoning. Now i want to ask. My 2 year old fell out his cot on his head 5 days ago. Yesterday he apparently zoned out for a while NOTHING could get his attention. Then late yesterday he started throwing up and having diarhea. He also does not want to eat. His much quieter than usual and wants to sleep alot. His eyes are sunken and he cries quickly. What could be going on