I feel that since you are not improving but rather worsening, you should see a doctor and get a brain imaging done. Although the injury
seems trivial, the appearance of symptoms after two days and subsequent worsening requires that you be evaluated for the presence of bleeding and haematoma
formation inside the skull. Please do not worry. Even if it is a haematoma, it can be easily treated. So just call your doctor and tell him that you had hit your head but forgot to tell him and that you are worsening.
Hope this helps you. Best wishes.