What is this lump on the inside of my knee after a thighplasty? (photo)

I'm 5 weeks post op from thighplasty and TT. I noticed this lump 2 weeks out. Doc said it was excess fluid but should go away with compression suit and massage. 3 weeks later it looks like it's getting bigger. It's right at the start of my incision which is going away. What do I do to get rid of it? It doesn't hurt and moves around when I massage it but doesn't shrink in size.