As well as the recommendations to get checked out,
I’d suggest raising your desk (and monitor) up.
Chop 5 bits of wood a couple of inches high, square-ish (from an old pallet or anything) and stick under the legs of your desk,so you can have your chair at a decent height and still get close to your desk.
Monitor can go on a box to lift it up too.
As a tall person sat a desk all day, this works well for me, and has helped to keep backache at bay. After changing jobs and not using my blocks for a couple of weeks, I could really feel the difference once I put a set back in.