Headache occasionally happens following mild headache injury but you should be cautious if that is persistent or increases along with vomiting then do NCCT Brain on Emergency basis & visit  a neurosurgeon asap

Hello. If there's swelling around eyes and blackish discoloration, you might have to get a simple CT scan done (if considering significant impact!)- especially to check integrity of bone. Watch out for worsening headache, vomiting, drowsiness, salt water sensation in throat. If any of these, consult in person/ Get CT Head. For pain any suitable analgesic is good enough.

Head ache is expected in mild head injury. If you have *headache - not responding to simple pain medications*, or loss of consciousness or seizures or black eye or if not on anticoagulants or no vomitings - then no need of further evaluation like Ct brain You can just take stmptomatic medication