It really does not matter what the cause of the headache is, one just treats the symptom (pain). You could have some surface pain from the nerves in the skin. They can be symptomatic longer than a related headache. They take longer to heal from the skin trauma.

The headache could be from the bump or anxiety over the bump or a memorized reaction to head contact.

Ice the area and go easy for a while, trying to relax.