Assisted shoulder external rotation in supine with stick

Lie on your back with your symptomatic arm on a pillow by your side.
Hold a stick in both hands with both elbows at a 90 degrees.
Use your good arm to push the stick across your body towards your symptomatic arm, turning the forearm outwards.
Do not allow your upper arm to move away from your body.
Move the arm back to the starting position and repeat and a steady pace.