Hi MelissaD, I've had extensive experience with a Seroma. I was diagnosed in 2013 & had all my treatment in 2014 with BiLat Mastectomy. My Seroma developed about 10 days after surgery and was quite persistent. My surgeon drained it heaps and heaps of times as did my Radio Oncologist. Eventually my surgeon put me back into hospital and "glued" the tissue down - this still didn't work. I ended up with an infection and 6 days in hospital on IV antibiotics and still it persisted - surgeon in the end decided to put in permanent drains which lasted 3 & 5 days and in the end he just left a little hole for the fluid to escape from and I wore a dressing over the spot. On his advice I took Neurophen for some time as this helps with the drying up of things and it eventually stopped. I had my surgeon completely baffled and he only just mentioned a couple of months ago that my case was a test case and that he had spoken about it at a conference he had attended where other surgeons were asking what could be done.
Hope yours sorts itself out eventually.