First, take a deep breath and step back for a moment. I have absolutely been in your shoes in the last six months. I finally, just three weeks ago, got control of "it." I practice S/T too, and what's a basic tenet?....backswing goes inside. This, as Sean Miller points out, leads to a very in-to-out swing, in which the hosel can lead into the ball.
I solved my issue by actually looking at KJ Choi's downswing....watch how he gets that right shoulder moving towards the target...probably Over the Top, but for chronic shankers/in-to-out swingers, its a good visual. Just thinking.."turn right shoulder toward target" on downswing cured my shanks...Certainly, this advice is NOT for everyone, but it worked for me. Good Luck!