What Causes Hard Lump On Neck In A 7 Year Old?

A egg sized lump has suddenly appeared on the left side of my seven year old sons neck. It s firm to the touch, but he gets no pain from it. I ve googled up on it with plans to get him into the doctors on Monday since he feels no discomfort however most of the advise points to cancer causing me to get even more worried. I was just after some advise about wether this is most likely swollen glands or if it could be something more sinister. It s situated in the middle of his neck but leaning more towards his ear rather then his collarbone. It appeared within the space of a hour I would guess and it s not painful or tender, there s no rash or red skin around it. It s just a hard lump that I can get my fingers round. He was I ll five days in the last two weeks could this be a lasting effect of his illness??? Any advise would be appreciated thank you...