I definitely recommend that you get in to see your doctor
as soon as possible. Every time you have a head injury
and there is concern for residual symptoms, you need to get checked out to make sure you have not had any serious neurological injury.
Your doctor will be able to perform a complete exam of your head and neck as well as a neurological exam. With these, they can rule out any major bony injury to the skull or spine, and they will also be able to rule out any serious neurological symptom.
Assuming this exam is negative, then it sounds like you are probably suffering from a concussion
. A concussion is a minor form of brain injury which typically causes a range of symptoms such as headache, fatigue, and memory loss. Most of the time, the treatment of concussion is support, as the brain will slowly heal itself over time, although it may take weeks for the symptoms, such as the memory problems you are reporting, to resolve completely.
Your doctor will be able to confirm the diagnosis of a concussion and give you more advice. Make sure you get plenty of rest and stay away from contact sports and other dangerous activities until you recover.