My son has a bump behind his left ear .he is 15. It is hard totouch and not painful unless you press really hard

I simply wouldn't take any advice here other than to take your teen to see your doctor. No one here can say with any certainty what it is or isn't. We could say it could be this or that but that may only cause you further concern or ease your mind and deter you from getting him any medical help that he may really need. Please just take your son in. I wish you both the best! And let us know how it turns out.

Sorry Tawny, had to spread the love.

Yes Kamilla, here we can only guess since we are not able to do a complete family history and physical exam, correct diagnosis can be made only by your doctor.

You may get many answers here such as the one I was going to give (could be a swollen lymph node, has he been ill recently?), but would could be wrong and if we are, and you take to heart the advice you got here, it could be dangerous to your son.

Please take him to the doctor for a proper diagnosis.