My sister has been complaining of severe headaches from the base of her neck. She has had an MRI, CAT scan and X-ray. Everything has come back ok with the exception of the x-ray. A chiropractor has been treating her because her neck is out of place. Now she went in again because the pain is not going away and they are telling her they will order a CAT Scan because there might be damage to her blood vessels. Is that serious? Can that be treated? Would that cause the pain?