Welcome to HealthcareMagic. If you got blunt injury
of head and had no loss of consciosness, no bleeding from ear, nose, did not have any seizure/ convulsion
and got checked by a doctor, then there is not much to worry. But at times some kind of injuries might be there which might present with some late manifestations. Headache after a punch is possible due to be minor injuries. Although I would advice you to get an MRI
brain done. And do consult a neurologist
. Get well soon.