DS banged his forehead yesterday around 4pm, despite being in a little pain was ok. He played out in the garden for an hour or so and was fine, but couldn't face eating any tea which is unusual for him. He was normal this morning before school yet by 11am he had been sent home after vomiting in school. He looks pale and is with a headache ( he's had calpol) and been sick twice since coming home from school. Is it just a bug or an after effect of banging his head?