hello, im a 16 year old girl and im experiencing the same symptoms as your son. I too have a lump the size of a grape that i can move and is tender. I also get lightheaded and nauseous throughout the day and feel like im going to puke. i am going to the doctors next week on thursday to get it checked again cause the doctor told me that i should watch it and if its not gone in a month we will need to check it out.
soo if you find anything out please please tell me,
and i will do the exact same for you. :)