Frog stitching is my least favorite thing to do when quilting and the birds nest are usually caused by the upper tension being off on your machine. Before putting your quilt back on your machine do a practice piece of 3 layers to check the tension. Don't be afraid to tighten it or loosen it. When it is fixed quilt away and no more frog stitching. Oh yeah, you may want to use a safety pin to mark the places that you will need to re-stitch on your quilt top. The safety pin makes it easy to spot those area when all the frog stitching is done. I can't wait to see this quilt.