Yes. It is not uncommon for someone to suffer severe harm in an accident and still feel alright immediately afterward. This can happen for several reasons, including the rush of adrenaline that follows in the wake of a traumatic injury accident.
While adrenaline may mask the symptoms of your injury for a time, the harm you sustained is still there and needs attention.
If you hit your head, lose consciousness, feel a tingling sensation in your arms or legs, or have any doubt about the extent of your injuries, go to the emergency room right away. There are a few exceptions to this general rule, but they are limited in scope and application. If you fail to file your claim in time, you are prohibited from seeking any compensation from the negligent party through the courts.