Since your accident happened a few years ago your condition has become chronic, so don't expect a miracle. It will take some time. The more correction you receive relative to the biomechanical distortion, the longer you will be able to go without the recurrence. In the future, when the doctor has your problem under control and you have a flare-up, it may only take one adjustment to get relief for several weeks or months.
Yours in health,
Chiropractic has been proven to be effective for headache treatment. Depending on the cause of your headaches, which can vary widely, chiropractic should be a good option. Google local chiropractors in your area, read their reviews, and ask family and friends who they recommend.
This is copied from the Duke University Headache study:
"Spinal manipulation was associated with improvement in headache outcomes in two trials involving patients with neck pain and/or neck dysfunction and headache. Manipulation appeared to result in immediate improvement in headache severity when used to treat episodes of cervicogenic headache when compared with an attention-placebo control. Furthermore, when compared to soft-tissue therapies (massage), a course of manipulation treatments resulted in sustained improvement in headache frequency and severity."
FCER Duke Evidence Report Exec Summary