not knowing the type of spider (venomous or not) or the age/wieght of your son . i would advise you to seek medical care. an area of swelling the "size of an orange" is very concerning. take him asap. i was bitten when a teenager in the bend of elbow. had a bubble full of puss. had to have it lanced. seeped puss for days.
my son was bitten by a spider and now it is red and swollen but doesn't hurt him. what should i do? . the swolleness is the size of an orange but does not hurt him. he doesn't have hives or fever. should i take him to see his pediatrician?