I'm an older player (66) and have only been playing for 6 years (not counting 2 in junior high school 50 sum years ago. I have recently developed an intermittent problem during arco passages. My right arm will tremor, sometimes sever enough to cause the bow to bounce off the strings. I've been to doctors and been advised it's not Parkinsons, but some sort of application specific tremor which might be treatable with botox injections (SAY WHAT?) I'm not inclined to go that route. Does anyone have any experience with this problem?