hi jenjams, does the lump look like one of the lumps that is normally on the areola area? but filled with fluid? I ask as when DS was a few weeks old I had a swelling of one of the montgomery tubercles (i think thats what they are called???) on my left breast, on the areola, it looked like a big white head, I went to the doc who said that sometimes they can get filled up with milk and it gets trapped, then its basically like a big zit.
mine was still relatively small then, I kept putting hot flannels on it until it burst and released the tapped milk (or pus eww) then kept it as clean as possible. it was only as painful as a zit would be.
Dont know if its the same thing or not, but I hope you get it sorted quickly.

oh, it also really hurt to feed at the time as DS would aggravate it when attaching and latching and sucking as it was in that area.