Is this fat, seroma or hematoma? How to tell the difference? Cat scan doesn't show any fluid build up, but I'm draining (Photo)

Original surgery 4- 7-2015, after an infection wore a wound vac between June and august 2015- September 25 was stitched up and been healing with some one and off draining from my tt line. Dr says I have no fluid buildup, but when the tt closes completely it opens again about 2 weeks later.My left side is also bigger than the right side,swelling or fat? A few days ago I felt a hard lump now I see this rash where the opening for the incision was located. Are there any dr who will do revision ?