First 3 cheers for talking about tendinitis rather than RSI which is a horrible term which describes 2 different problems with diametrically opposite treatments. One is the tendinitis we have all come to know and love which begs for rest and the other is the pain you get in a muscle that gets ignore all week and hammered at a session and begs for exercise lke those muscles that the Good Lord stuck in front of your shins in case you ever felt daft enough to be a drummer! My own experience as a doctor with a melodeon was cured by me having the sense to steer clear of my colleagues and go and see Bob Cann (Lord rest him) who sorted out a few playing techniques and the shoulder soon sorted itself out. Sadly this advice may come too late to some poor souls who may come to need and benefit from steroids the same way the Titanic would have benefitted from a few more lifeboats, but there's no substitute for listening to what your body tells you once or twice in a while just as there's no substitute for missing flaming great icebergs when steering the unsinkable!