Bump on nipple? I've had for awhile but since my surgery it seems to have nearly doubled in size. (photos)

Since this has been present for years, it is most likely a Montgomery's tubercle with some blockage and sebum collection. Your plastic surgeon can easily numb this up (local anesthesia) and remove the offending spot, just like removing a cyst elsewhere. A tiny scar would be all that remains. It is nothing worrisome, but since it is enlarging, can be presumed something worthy of surgical attention. Best wishes! Dr. Tholen

Hello
dear, thanks for your question and provided information as well…
I have to say that you are still early on healing process, it is too soon to
determine how your results are going to be, per now, they look very nice and
beautiful, you can have one bigger than the other, feel swollen and also have
bruises and open wounds, it is normal and that can happen for the first 3 to 4
months until your implants have settle in. I recommend you to wait and keep
using your post surgical bra, that will help you with the shape and support!!

The bump is likely an obstructed lactiferous duct or Montgomery gland.  However I would suggest that she see a plastic surgeon for an examination and possibly an ultrasound.