Twist your hand around
A few years back I ended up having some injections in my elbow and multiple appointments because I was really struggling with continual pain. The decision was made to operate, even though this was by no means a certain cure, but the doctor suggested I speak to my employer first to see if some new equipment might help first.
A lady visited the office where I worked and offered a mouse like the one above, a mouse that allowed me to control the cursor vertically. She explained to me why it might help and I tentatively accepted the idea.
Try this-
Sit down at a desk and allow your hand to lie with your palm resting on the surface. Concentrate and you will feel a slight pull on your elbow. It is very slight, but when you move your palm upright that pulling feeling disappears.
Imagine doing this for 8 hours a day, just as most people do with a traditional mouse, and that slight pull can become a big problem over time.
I used the mouse for a few weeks and the pain disappeared. Three years later and I am still using a vertical mouse with no pain at all. And no operation was required either.
Sometimes the simplest solutions can bring the biggest benefits.