Hi.
Noted the history about your 5 year old son getting a
bee sting - the first time swelling took a day to develop but the second time sting caused immediate reaction and the swelling was immediate and spread up the arm.
Yes, this is because now his body has got sensitized to the venom of bee and there can be a serious problem next time on bee sting.
ER must have surely given an antihistamine and
steroid.
He can have neck, throat swelling and anywhere else too if the bee sting is repeated.
Hence you have to be sure abut eliminating bees from your area, Use protection for the son, avoid contact in such places where bee sting is possible like avoid areas infested by bees.
Carry antihistamine and steroid all the time and instruction the son with written chit so that teacher or anyone else nearby can give the doses.
Hope I have answered your query. Let me know if I can assist you further.
Regards,
Dr. T. Chandrakant, General Surgeon