I highly recommend that you see a physical therapist. That's when my situation started improving. An ergonomist recommended this mouse to me and it's been real

I highly recommend that you see a physical therapist. That's when my situation started improving. An ergonomist recommended this mouse to me and it's been really good for me (better than the Logitech MX Master I had been using): https://handshoemouse.com https://handshoemouse.com. Also, setting my desk height properly helped, I think. It's hard to find desks that are low enough but I bought an Ikea adjustable height desk that goes low enough so that my elbow is level with my hands when typing.