I would call it quits on the conservative approach and go back to surgery, cut out the seroma cavity, place a drain and let it heal definitively. Nothing is improving and you are increasing your risks with sclerosis.
Thanks for your question about seroma. Seroma is very difficult to treat, in some cases, and they do sometimes require surgery to treat when they do not respond to more conservative treatments such as repeated drainage and sclerosing. Since you're 3 months out, perhaps discussing with your plastic surgeon your options now and considering repeating sclerosis versus surgery to remove the seroma cavity would be appropriate. After many months, the seroma cavity is well formed and is less likely to respond to conservative methods. Work closely with your plastic surgeon as best as you can to formulate a good plan. Best wishes always, Dr. ALDO