Back in the 90's I switched from graphite shafts on my irons to steel. Since then, I can always tell how well I hit the ball now from my elbow. If I hit it pure, fine. If I mishit the ball my elbow hurts that night. The docs will tell you rest is the best fix for tendonitis, but then you miss golf. Try Naproxian. I now have some tendonitis in my left knee (Right handed = left knee/right elbow) so I take a couple before I play and a couple after. It helps.