Brachialis Tendonitis

As an armwrestler, Ive been fighting tendon issues for years. But this is a new one. My brachialis aches everytime. I read that the brachialis is very active during isometrics, which is exactly what we try to do…keep a solid 90degree lock at the elbow while shifting the body. Now it hurts so bad its shutting off power to the muscles as a safety mechanism. Anybody have any suggestions? What is typical rehab for this?