Painful, lump in rib cage just appeared a week after lumpectomy

KARW41

I've been searching to see if there is anything about this, but I don't see anything. I've recovered just fine from a lumpectomy with 9 cm+ (not all resected) DCIS. However, today, I noticed my rib cage sort of hurt and looked in the mirror and a lump has appeared in between two ribs. It seems decently well formed as a small lump, but it is soft. It would seem weird if something leaked to the rib cage from the breast a week after surgery?? Also, it is definitely not swelling. It is a formed lump down there, away from the breast a bit. I go to the doctor on Monday for the post-op visit. I had a video visit with another doctor today, who said a tumor board looked at my "case," and they agree with my mother's multiple cancer history a prophylactic, bilateral mastectomy with Tamoxifen until then is best. I just now saw this lump. It is maybe 1/2 inch and looks kind of roundish. It DEFINITELY wasn't there before and it does hurt. I noticed it hurt when I lifted my right arm straight up. I don't mind the pain but I just hope nothing bad "seeded" down there or something is not suddenly "growing" there. It is quite close to the skin. Has anyone heard of this after lumpectomy. I apologize if it is on here, and I just don't see it. Maybe I don't know what it is called?? Thank you.

KARW41

Ooops, sorry. I think I found the answer to what it may be: https://rethinkbreastcancer.com/five-things-to-know-about-cording/