I had a somewhat similar problem after the first surgery. I had an abscess in my pelvic floor that produced a 9x9 cm fluid mass (so I basically had a baseball sitting in there). It was drained (the drain stayed in for about 3 weeks) and I had to spend a week in the hospital.
My problem was a streptococcus infection, so they had to pump me full of antibiotics and flush the thing out every few hours, but it did the trick. Everything's fine now. Hope this helps.