Good advice,,, I had Tendonitis really bad huge discomfort even through the night, i'd wake up with pins and needles and a dead arm every morning.
Enough was enough, i saw the doctor he told me to take 6 weeks off or change jobs, I am self employed and love my job so no chance.
Instead i looked at the way i worked, i had been doing lots of hedge cutting (major cause of havs (hand arm vibration syndrome)) so i stopped that, using a prussik loop was putting huge pressure on my arm especially when body thrusting, so i stopped body thrusting to asscend, changed my knot to a tended hitch that allowed me to pull with both arms and hold my weight with the left keeping my arm locked straight in a more comfortable position. Stopped using the top handle saw one handed so much etc etc
Basically anything you can do to balance the work load between both arms, even things like feeding the chipper with your left arm, using the silky with your left hand, alternating your grip on the groundsaw i can now use a groundsaw with either my left or right easily and accuratly, little things like when using a groundsaw low to the ground support its weight by resting your forearm on your leg (without pics this is probably hard to understand)
All these little things over the course of your long career will cut down the stresses you put on your body.
I also went for physio I choose a Chineese threapist near me who suggested massage, heat treament and accupuncture basically this helps to stimulate the blood flow to help the body heal naturally over 6 weeks twice a weeek at £15 per half hour treatment, seemed to work for me.
Haven'thad a major problem with tendonitis for 2 years now, i still get a little pain as i've damaged the sheath my tendon/nerve runs through, this will never heal without surgery but the pain is bearable and i am not handicapped in any way so why bother with the surgery.
I hope you find a solution to your problems.