It seems from the history that your son had suffered a injury to the head following which he is having symptoms of dizziness, headache, nausea...
All these symptoms indicate a probability of concussion head injury
and requires evaluation to rule out brain edema
and concussion injury
as a result of injury.
Nurofen is a analgesic
drug and is used for pain relief.
Hence I advice you to consult your doctor for examination and treatment accordingly.