Hi,
How are you?
There is a good possibility that your headaches are related to the cervical spine damage that you suffered during the accident.
I would suggest you to continue with the neck brace and get a CT scan and MRI of the cervical spine done to find out the exact cause. It could be a cervical dislocation.
The possibility of aneurysm at the moment does not seem very likely. Cervical causes need to be ruled out first. Take care!
Did you have an MRI or CT scan of your head done??? If not, you should have this done immediately. While it may be nothing, you should still have this checked out, given your circumstances. This is not to say that it's something you should begin worrying about--but you may have needed more than a neck brace following your accident. If you suffered any kind of neck injury or trauma to the head, your head should be looked at immediately, and usually having an MRI with contrast is the way to go.
Keep us posted and please get this taken care of as soon as possible!