First hang in there Lynzy. I would highly recommend an expanded Thyroid panel, and even submit for evaluation to Dr Jean Dodds,
www.hemopet.com. The people on the phones are very kind, knowledgeable and informative. As is Dr Jean Dodds, you could even email her with your dogs brief medical history, and see what she has to say.
Now swollen lymph nodes are at their most benign just a sign of infection, and or the immune system getting overloaded for some reason(s).
Now with Zoey's case, it was quickly apparent there was something really wrong. How quick? Within 48 hrs. On a Sunday we felt a quarter size "swelling" over her thyroid (that is on the neck, approximately where a human's Adam's apple is) by Tuesday it was the size of a golfball, by Wed am, her jaw was swollen, the golfball grew to a tennis ball size, her chest/armpit area was swollen, and her groins, and her lymph nodes on her hocks. I knew then we were in trouble.
I won't tell you not to worry, because we do and that's that. But don't think the worse. Also I think after this run of tests are done, an internal medicine specialist might be in order.
Food allergies might also be a probative cause, and something to rule out.
Then environmental causation
Water - what kind does she drink? I might try out distilled water for a month or so and see how she does.
Hugs to you and Miss Mini. Sometimes I wish "all of us" were actually much closer so that we could exchange more than "virtual" hugs.