Hi and welcome to our community!
I am sorry to hear of all the difficulty you have been having with seroma following your reconstruction.
I don't know a lot about resolving a continuing problem like yours, esp. in the back, but here is a link to a thread discussing a similar problem following breast surgery:
http://www.medhelp.org/posts/Breast-Cancer/post-lumpectomy/show/1734130
Perhaps some of our other members will be here later and have a better answer for you, but for now, I wanted you to at least know that you were heard and welcomed.
Best wishes,
bluebutterfly