I am sorry, but I am also unable to help you. I really wish I could.
I was doing a search tonight for "swollen lymph nodes on the back of head and under chin/jaw", when I came across this thread.
My daughter who is only 11 years old has this.
I origionally took her to the doctor a few weeks ago for a lump at the back of her head, an inch or so above the hairline and to the left side. I thought it was a lymph node, but her doctor said it was a cyst and that we should just watch it. Well, we have and there has been no change.
Also at that visit, the doctor noticed that she had some swollen lymph nodes under her chin on both sides. She did a strep test which came back positive. (She had no signs of strep, but I had had it the week before). So, she was put on antibiotics. My daughter completed the antibiotics a few days ago.
So, now tonight I go to check the "cyst" and my daughter tells me that she noticed a new bump growing in the exact same spot on the back of her head, but on the right side. She said it has been getting bigger. I checked and sure enough she now has one on the left back side of her head that is twice the size of the one on the right. She also still has swollen nodes under her chin on both sides. Again, she has no signs of any illness, no sore throat, no fatigue, no headache, no pain, etc.
We are off to the doctor's again tomorrow but I was hoping someone might have some info for me. The only other thing that I think might affect this all some how is that she was diagnosed with Mono 2 years ago.
If any one has any thoughts or ideas I would appreciate hearing from you. I can only think of the worst case scenarios.