Yes, you can experience a concussion without an external impact to your head.
A concussion can happen during forceful backward and forward motions like those occuring in whiplash – typical in rear-end collisions.
Concussions, either from whiplash or a blow to the head, have the same or similar. Even if you didn’t hit your head but feel any symptoms noted above, please get yourself checked out at either your local emergency room or your primary doctor.