Really poor cueing by the field coach

He told me to "lead with your chest" when throwing shot put. That meant the shot came away from my neck, and my elbow got behind me. 4 years later, my shoulder is trashed, and I never had time to not use it and let it heal. It gets a little better, it gets a little worse. I've gotten tired of the worse part and decided to try some actual rehab strengthening the supraspinatus