If you are suffering from pain after an accident the first thing to do is to see your GP at your earliest convenience. If your injury is related to work or an insurance claim you will need to see your GP who can start the process of referral and obtaining your claim number.
Obviously some injuries are instant but it's worth remembering that whiplash type injuries will often take a while to fully manifest themselves. The body often goes into hyper-protection mode as a safety measure after a traumatic incident. Your body then starts repairing itself after the event. The repair period is when the pain can really start.
Physiotherapy is one of the most effective healing tools available. It can calm down the muscles and mind down after a traumatic incident. It increases blood flow to the muscles, which subsequently increases healing.
Your physiotherapist will explain your injury and what they can do to help you.