I was in an accident 3months ago had x-ray of my neck due to whiplash. i've been seeing a chiropractor but it still hurts. should i get an mri?

Yes if not improved: If you are still hurting without any real improvement or if it is feeling worse, then a MRI would be indicated unless the pain is mild and not affecting your life.

Whiplash: Unfortunately whiplash syndrome is difficult to treat and diagnose for that matter. I would get a cervical mri, but remember that the findings on MRI may or may not correlate with your symptoms.