Hello Don't worry.. hematoma will resolve without treatment in some time Having said that kindly consult local opthalmologist and rule out green stick fracture or any blunt injury to eye

Ideally any injury around or to the eyes need a complete ophthalmic evaluation including an X-ray. Recommend you to consult your eye doctor at the earliest

Cold compression with ice and get a X ray done to rule out orbital fracture. Ideally consult an ophthalmologist for further evaluation.

First of all check vision by showing him object  of interest. Then check if any bleeding from nose or ear or child is drowsy Feel the hematoma with your palm and feel if crackling sound is felt suggesting air bubbles in the swelling If all these are ok Only cold compress for a couple of days should make him ok Any fever or worsening will herald evacuation/xray/Antibiotics. So that part is for doctors to decide. Better show him to doctor