Mosquito bite reaction !

This was my son last summer ! Every year his mosquito bite reaction is getting worse ! Thank fully this year we were able to keep him safe from any bites on his face or neck ! He got one on his lower leg and it blew up for a few days ! Does anyone else have a child who has extreme reactions to bug bites ?! I'm scared that his throat is going to close up if he gets one on his neck! I asked the doctor about an epidemic but he said it isn't like a bee sting or anything .. so there is nothing I can do besides give him Benadryl ! Any advice will help ! Thank you !