Mystery Illness?

Hello. Since mid-December, I have been having swollen lymph nodes in neck and under armpit. I have no other symptoms. I have been to several doctors and had a CBC, differential, ESR, metabolic lipid, thyroid, lyme, EBV and monospot done, that was normal, except I am positive for EBV. I have depression. What is causing my nodes to swell? Thank you.