How To Treat A Large Lymph Node On Neck?

HI.MY NAME IS HELEN. IHAVE A SON 12 Y.O. IN GRADE 2 HE HAD SURGERY TO REMOVE LYMPHO NODE ON HIS NECK SIZE OF PING -PONG BALL. IT IS APPEARED SUDDENLY, OVER THE NIGHT. HE COULD NOT BREATH,HIGH FEVER.... HE WAS VERY SLIM BOY BEFORE OPERATION, BUT RIGHT AWAY AFTER THE OPERATION HE STARTED GAINING WEIGHT VERY RAPIDLY AND NOW...... HE IS ONLY 12 AND 240 POUNDS. HE IS NOT EATING MUCH DOES NOT EAT JUNK. EAT ALOT OF FRUTS, VEGGIES, A LOT OFF EXERSISES-.DOCTORS IN MY TOWN TELLING ME HE IS FINE .BUT I KNOW HE IS NOT FINE.IT IS NOT NORMAL.BUT DOCTORS IN MY TOWN REFUSED TO SENT HIM TO ENDOCRYNOLOGIST TO EVALUATE HIM. IREALLY WANT TO SEE SPESIALIST WHO CAN EXPLAIN ME WHAT IS HAPPENING IN MY CHILDS BODY AND FIND HLP TO FIX THE PROBLEM. MY SON IS CRYING SOME TIMES MOM, I DO NOT WANT TO LOOK LIKE THIS. PLEASE, SOMEBODY HELP ME TO FIND THE PROBLEM AND HOW TO FIX THIS. THANK YOU AND GOD BLESS.