it may be some kind of insect bite leading to this much swelling in such a short time involving even forehead.
though some viral and allergic conjunctivitis
may lead to eyelid swellings too.
you should get him checked by an ophthalmologist preferably who would be in a better position to tell about this.
for the time being you should continue cold
compress, and paracetamol
syrup can be give if there is pain.
particularly you should be very watchful about any symptoms of acute pain or redness
of eyes or any complaint about vision.
thanks for the query
wish your child a rapid recovery
Dr. Amit Kumar