Focus on the neck . Depending on the severity i would do pt on the neck. Headaches are likely cervicogenic.
Depends. If it is a severe headache ("the worst headache of my life") and you also have neck pain then you need to go to the emergency room and get evaluated. If it is a mild headache and the neck pain predominates then you might have head pain coming from the cervical spine and that needs a different and less urgent evaluation process including history, examination, and possibly diagnostic imaging.
Need evaluation. Pain in both the neck and the head can be seperate issues or the result of dysfunction in the upper cervical spine. A proper evaluation by a neurologist or pain specialist along with radiographic studies (MRI) can help to determine the cause of your pain and will help direct treatment options.