You are absolutely right: lymph nodes normally swell and shrink in response to infection.
Mine swelled to the size of a quarter the very day I gave birth. It was an unmedicated, unintervened delivery, but it was in a hospital so I imagined at the time that I was fighting an infection without presenting a fever (since infectious agents always reside in hospitals). It's hard to tell whether your body is just exhaisted from birth or actually infectious after delivery, you know, so nobody was too concerned. Especially when it decreased within a week to the size of a dime.
It has been 6 months, though, and since then it has shrunk it's the size of a pea. I was examined yesterday and the internist scheduled me for bloodwork and a sonogram with possible biopsy on Friday.
The internist was very reassuring, though, despite her concern that it get checked out promptly. She let me palpate a nodule of hers, on her neck, which had caused her to worry 3 years ago. She opted not to have it biopsied at the time because of the complexity of the neck region where it is located, but reminded me that if it were lymphoma she would already be dead.
I guess that lymph nodes are possibly just as liable as, say, the lungs, to becoming fibrous when scarred by infection. I haven't read whether this is true, but I believe that's the type of tissue these cystsic nodules might be comprised of. Does anyone know? I'm not a medical professional.
At any rate, I've been so relieved to read these posts. I mean, it's unfortunate that so many of you have had the same scare, but I'm so thankful that you've felt comfortable enough to discuss such a personal concern. So I guess I should say, thanks