When you have railroad tracks and bird's nests on the back of your quilt, the top tension is too loose, and when you have the railroad tracks on the top, your bobbin is too loose.
Tension problems are the bane of quilter's existence! LA quilters work every time to balance their stitches because the perfect tension on every quilt is affected by the material used in the quilt, the batting, the thread on top and in the bobbin, and the tension of the quilt on the frame.
The only good thing about railroad tracks is that they are easy to frog! Hang in there, it does get better!!!