How does it feel; soft, hard, fluid filled?
Is it red or warm?
Do you have sore throat, boil or skin infection in the neck or face?
Its kinda hard ...don't know about fluid....warm, but I've been pushing on it alot.
It is likely to be a lymph node. Pea size of lump are most of the time not significant. A pain, warmth and tenderness point to some infection around the area. The lymph nodes are affected by this infection as they are our first line of defense. Almost all of them would subside on their own. You can wait and watch for a week or so. If this does not decrease in size, you can talk to your doctor, who would give you a course of antibiotics.
Please feel free for your follow up questions.