Hi... Welcome to healthcaremagic forum.
1. How long ago did he sustain the injury??
2. Did he lose consciousness after the injury??
3. Is he having recurrent vomiting
, reduced activity/drowsiness
If answer to question number 2 and 3 is yes, then it is a serious concern which needs immediate attention.
Else there is no need to panic. He may need Xray skull/Scans to look for possible skull fracture
which most often do not need treatment...
Hope I have provided answer to your problem.