I agree with japdip totally and I would get a second opinion. One member on this forum told us about how she had similar pain like you and that it was not taken seriously. Finally, and not because of this, this lady had reconstruction done of her breasts and the Plastic surgeon found a pocket filled with fluid in the hurting breast and removed it. She never had that pain again since.
You also do not have to put up with them hurting you like that during a mammogram.
You tell them, and your doctor, or both that the pain is unacceptable and you want an order written that demands they do not hurt you. If the doctor thinks that may not be entirely possible then you make sure you have a prescription filled for vicoin or percocet to take before the next procedure.
Good luck, Katrin
Showing no disrespect to your Dr. but I think a second opinion from a Breast Surgeon would be in order. Seromas do not last forever ..... Either by drainage or by placement of another drain for a short period of time they will eventually stop filling and the tissue will "stick" so that the void will be no more. The only suggestion I have as far as your upcoming Mammogram is to take some type of over the counter pain medication beforehand to help with the discomfort. Regards ..