Hi Susan,
After my first mastectomy in mid September I experienced a build up of fluid two days after coming home. It looked like my breast was growing back and was quite uncomfortable. I was really stressed and contacted my doctor immediately. He was very reassuring and seemed completely unfazed. I arranged to see him the following day in between his surgeries. I was really anxious about the idea of having it drained. It was over and done with in about 2 minutes and I did not feel any pain at all - much to my complete surprise and I was much more comfortable afterwards . When I went back to see him for my post-op check up the fluid had built up again - it looked like a waterbed on my chest. It was drained again and after that I was fine.
According to my doctor it is a relatively common experience and can be dealt with easily. It does settle down eventually.
Good luck with your continued recovery
Karen