Swollen lymph nodes are an extremely common trigger for health anxiety - the forum is full of posts just like this.
For what it's worth, I had 2 episodes of pretty severe anxiety triggered by something lymph node related. Most recently I noticed one palpable node on the right side of my neck, and a smaller one on my left, where I had absolutely convinced myself was something sinister. Two doctor visits, one CT scan, and a month of blind panic later, turns out it was nothing but my own anxiety. I can still feel them if i look for them, and it's been about 9 months since the first time I noticed them.
What I found extremely helpful was challenging anxious thoughts. For you, focus on the fact that (1) You're not even sure what you're feeling - if even you think it's probably muscle or bone, then it's certainly not clinically swollen lymph nodes. (2) If you think something (swelling in this case) is due to your imagination than it almost certainly is. (3) Appetite loss is a common anxiety symptom, probably due to you getting yourself worked up over lymphoma. (4) As for the lumps on your neck, 'being there all the time' is in fact what all lymph nodes are - they're permanent fixtures and part of our anatomy. Lymphoma tends not to be particularly sneaky - if the lumps haven't swollen to the size of golf balls over the past 4 months, then you're fine.
Hard to see when you're in it, but this sort of thing is just your anxiety running wild. Try to relax and enjoy the new year!