I wish I knew what to tell you, that must be awful!!!!
I had a lumpectomy on 11/15 and have been having some burning under my arm when I lift it just so so, its really uncomfy so cant imagine having it around the nipple area....
I posted on another web site about the burning and most of them said it is probably the nerves reconnecting , rewiring themselves and that it will go away after awhile....I have been using a heating pad and that seems to have helped (not sure if it will in your case, but might be worth a try)..Have you spoke to your Dr. about this yet?
Also want to say how happy I am to hear that your mass was malignant, so many of us here hoped to hear that word but heard others :(
Keep me posted and hope I was helpful in some small way...