I went through that a couple years ago and thought for sure my guitar playing was over. I had 2 cortisone shots and after second I think I would have been far better off without either. They make the pain go away, once the pain from shot dies down, but they thin the tendon too. So after second shot I actually tore a bit of muscle because I should have been avoiding things that would make it worse. With no pain, I plowed ahead and caused worse damage. Physical therapy, two 6-week rounds - 3x/wk - about 6 months apart, did the trick finally. There are some dumbbell exercises you can do with 1,2 and 3 lb weights that PT should show you. I kept that up for another 6 months and it's finally about 98% healed. I still can irritate it on long motorcycle rides and extended acoustic guitar playing while sitting. The moment I feel it beginning to ache, I stop what I'm doing and do the massaging like mentioned earlier (except on bike, I can't actually stop but will massage at stop lights and such.