Thanks for the query
From the information that you have provided it seems that you have a fracture
of the nasal septum
which was taken care of promptly. Headache after such an injury
can be due to many reasons. First possibility is infection of the sinuses
. Sinuses are cavities in the skull bones. Second possibility can be a growth or hematoma
following injury in the nasal area. Hematoma is a swelling consisting of blood.
Third possibility can be a missed fracture of the facial area.
To rule out all the possibilities and to get proper treatment you need to go back to the specialist taking care of the fracture.
Hope I answered your query