Thanks for writing your query.
Headache usually result after head injury
even if there is only soft tissue injury
. You will feel better in few days after proper rest.
You should feel concerned if following are noticed :-
1. Persistent headache
3. Irritability or confusion
4. Loss of memory
5. Difficulty in balancing the body
6. Loss of conscioussness
7. Bleeding from nose or ears
If any of the above symptoms develop, get yourself immediately examined by a Neurophysician and get a scan of your head done. Take proper rest for speedy recovery.
I hope this is helpful to you.