I've done some research on it... seems the main treatments across the board is pressure dressings (but you can't since yours isn't an extremity), massage (already doing), exercises, and diet elimination (cutting back one type of food group at a time to see if it helps).
http://www.mayoclinic.com/health/lymphedema/DS00609/DSECT...
http://www.cancer.gov/cancertopics/pdq/supportivecare/lym...
Antibiotics are the ONLY medication used for this issue - and majority of them are breastfeeding friendly. Seems many medications cause the issue to worsen, except antibiotics. If you need pain meds, most are safe for a breastfeeding toddler.
The prolactin you are producing in order to breastfeed actually helps BOOST your own immune system. So if you get this sick WITH nursing, imagine what may happen when your prolactin levels go back to normal.
I think your best answer is to go to another Dr to see why the massages aren't working. Maybe you've been misdiagnosed. Enlarged lymph nodes are the symptom of a few things. Have you been tested for lymph cancer, cat scratch disease and MRSA?