Since he was not accustomed to using his left arm for everything, he developed tendinitis in his left arm as well. It is possible to compensate unconsciously. When Vivian's shoulder tendinitis first developed, she took anti-inflammatory drugs to the point where she didn't feel any pain except when she pushed her arm way back. So one day she decided that the woodpile had to be re-stacked, and proceeded to do so, without feeling any pain. The next day her biceps tendon ached badly.
Most drug stores carry various types of braces which give support to wrists, elbows and knees.
They can be useful in enabling you to use the joint without aggravating the inflammation. A wraparound bandage can do the same thing. Surgery is a treatment of last resort, but in exceptionally severe cases it may be the only way. It is fairly common for carpal tunnel syndrome, which seems to be less responsive to other treatments. The real bottom line in preventing, relieving, or curing tendinitis is to minimize stress in your life.