Fingertip wound stitches--?

The other night my finger got caught in an immersion blender and I sliced off a large chunk at the tip essentially what makes up the fingerprint area down to the bone. It was connected by a small piece of skin so the chunk stayed on in a flap. I went to the ER and got five stitches to reattach the flap. It healed well for the first few days but then I tweaked it in a strange way and felt like I had ripped a stitch or something, it was just extremely painful. Later that night I noticed what looked like a 'bubble' of flesh between two of the stitches. It is extremely sensitive to the touch and seems to be growing, the piece of the flap that previously had blood flow seems to be turning white. Does anyone know what this little 'flesh bubble' could be?? Is it something I should be concerned about? Should I see a doctor about it?