My G.P. said she doesn't know what it is but isn't worried about it - well good for her!!!
I wonder if it could be the sort of thing you experience. At the moment mostly all my joints are cracking. Am going back to G.P. on thursday [tommorrow] will let you know if she has come-up with anything. Didn't get any answers from googling. Regards.
Haven't had the puffiness like that anywhere except below and to the inside of my knees -- it's about as much as if you cupped your hand rather flat. I don't know, but I'm guessing it happens after the bugs die and the fluid that's been building up in my knees escapes, and it goes to the point of least resistance. Then over a few days, it gradually disappears. I try to help it along by putting my feet up in the air and stroking each leg from ankle to knee for several minutes.
What you would do with a neck swelling, I don't know! Try googling ... but it would be a hard search to formulate. Let us know what happens.