Being rear-ended is not the only way one can suffer whiplash. A fall that “whips” the head and neck will have a similar result, and often takes a similarly extended recovery time.
Though the cause is different, my treatment plan is the same: rest, anti-inflammatories such as ice and topical arnica, gentle chiropractic adjustments with the Activator instrument, and active care as soon as possible (stretches and exercises) to assist healing.