Herpes or Sores oh Toddler

Hello everyone My almost 2 year old son has not been wanting to eat for the last couple of days....he has been drooling so much and had a fever I tought maybe he was growing another tooth ....then i checked his mouth and he has alot of sores on his tongue and gums he cries so much cause he cant eat anything just drink today he woke up with more sours on the outside of his mouth His doctor cant see him until tomorrow should i go to the ER for this?????