Have to start weaning two month old

I've just come back from a specialist after being referred by my doctor after I found a lump In my armpit about three weeks ago. Not linked to breastfeeding as its not painful and had an ultrasound to confirm it was an inflamed lymph node. I thought maybe they would do a fine needle biopsy but they are wanting to remove the whole node under general anesthetic - I also have to completely stop breastfeeding and have no milk in my breast before I can have the surgery. I'm worried and sad about the health of my two month old if I stop...I'm not sure if I should wait a few more months? Anyone heard of anything similar or have advice?!