Whenever I ride, my right elbow (and much less frequently, my left) gets extremely tight and sore. I regularly change riding position (drops, hoods, tops), and stretch my right arm, but nothing seems to work.

The bike was originally fit by the LBS, and I've double-checked all my fit measurements based on a variety of references (books, magazine articles, etc.), and have made some modifications myself to test a variety of positions. My reach may be a hair longer than it should be (e.g. 0.5 cm too long by book standards), but that's my most comfortable riding position. I would think that if my fit was wrong (reach-wise, for example) my back would also hurt, but it doesn't.

Anyone have suggestions? Or should I just accept that maybe I have a touch of tendonitis and live with it?