Welcome to Healthcare magic forum.
It seems that your son suffered a minor blunt injury
to his forehead which doesn't seem to be worrisome at present.
However in infants one has to be precautious as they cannot communicate the severity of symptoms and their skull bones are soft which make their brain more prone to the impact of an injury.
So please be watchful and look out for development of any new symptoms like, vomiting
, convulsions(seizures), any weakness of limbs, fever , swelling or redness
around eyes etc.If any such symptoms develop then do seek prompt consultation with his pediatrician
If he has only mild pain, redness, swelling like a bruise he will most probably recover fully within a week .
Mild analgesics like acetaminophen
can be given for symptomatic relief.
So do not worry, but do be vigilant .
Hope that answers your query.