One option I can see is Put on "Miracle on 34th street". Begin taking out the stitches and don't stop until the area of fullness can be reasonably flattened. Might have to unpick a square foot or more. Pin baste the heck out of it and requilt.
If this is the back, and the front looks OK, you could just leave it.
Last edited by PaperPrincess; 11-21-2015 at 02:59 PM.