Not a nice problem.
Firstly look at your posture. The normal cause of a shank from painful personal experience is poor posture with too much weight on the toes. This encourages you to move into the ball on the downswing and thus hit off the heel. Your weight should be evenly balanced,
It is easy to setup with too much weight forward on the shorter
clubs so get this right first - always work from the basics through to more complex solutions rather than vise vera.
Once you have this right work on hitting the inside edge of the ball rather than dead behind the ball. Setup a range ball with the painted circle aimed inside left to outside right and aim for the painted area on the inside left (obviously!). This will encourage and inside out path and help avoid coming OTT and hitting off the heel.
Good luck....
JCBDB