What Causes Painful Lumps In The Neck?

My son is experiencing hard lumps in several places in his neck. NOT in the throat. He has been to his GP for this a couple of times and an ENT who performed a larynscopy (sp) in his office. These are painful and cause him to have lower energy levels, probably because they hurt and he's really stressed out about this. I have to take him to a specialist who will actually do something about this instead of just telling him they're probably lymph glands. No one has ordered any blood work. He has had an ultra sound that came up nothing found/normal, he is about to turn 20 yrs old