JITB - I have had swollen lymph nodes - but not in those areas. It couldn't be seen...only felt.
My first one was the left Clavicle lymph node. It was swollen and hard...and really hurt!
Then after treatment started, I got another one behind my right ear.
The one behind my ear appeared during lyme treatment and subsided within a month or two.
The Clavicle one was there prior to treatment and didn't go away until bart treatment.
I would say it's either Lyme and/or bart in your case.
Since they're not symptomatic all the time...it could be toxins are building up. Have you done any lymph massages?
Here's a link to a guided lymph massage that I have used many times
/www.youtube.com/watch?v=QA-wi0d7-Ro