Many of us have suffered a concussion or know someone who has had one in the past. A loss of consciousness and vomiting does not mean a person does not have a concussion. One of the most common symptoms of a concussion is a headache. If the headache is still present over a month later, other things may be going on. An upper neck misalignment can also cause headaches. If you have had a concussion and are still suffering from headaches, talk to an upper neck chiropractor to see if you have a misalignment present.