Disclaimer: You are probably not a doctor. If you are a doctor, you are not MY doctor. So officially you don’t know anything and I won’t do anything based on what you say. Also I’m seeing my real live doctor in about a week. I’m just trying to figure out what the likely possibilities are.
Background: I’m righthanded. I work on a computer all day. This involves mousing, and I usually mouse right-handed (though with a very ergonomic trackball - the Logitech M570 if that’s relevant).
In the past, I’ve occasionally had twinges from overuse but it always went away promptly (especially once I learned to mouse with either hand). Not in years, in any case.
But 3 weeks ago, I started having pain in my right wrist for no apparent reason. From the sketches at Wikipedia, the end of the ulna (#2) is tender to the touch but does not hurt when I move it; I experience some pain radiating between the bones for an inch or two toward the elbow; I also have a lot of pain around hand bones (ring finger bones mainly) if I move my hand wrong - enough so that I use “driving words” some times. That might be around bone H in the drawing.
It’s interfering with some activities - can’t use a knife to cut anything super tough, holding a pen to write is painful, getting dressed is painful. I bought a wrist brace which makes typing a bit easier (reduces the bad flexing somewhat) but has otherwise not done much. I’m mousing entirely left-handed - which, if mousing were the issue, should have helped.
If I rotate my hand in certain ways, it hurts. If I use my other hand to rotate that hand (i.e. don’t use the muscles etc. of my right hand), it does not hurt as much.
I haven’t fallen on that arm in… um, not as long as I’d wish, but it’s been a few years. I did break that elbow about 20 years back (it’s how I learned to mouse left-handed).
Carpal tunnel is the obvious thing that comes to mind but I always thought that involved pain in the fingers themselves, including numbness - I had some of that during my last pregnancy. Nada, this time. Maybe some kind of tendinitis? Some weird sort of arthritis related to the old broken elbow? (radial head, so nowhere near this).
And in either case, since splinting hasn’t worked (and ibuprofen isn’t doing much… maybe if I took that more regularly!), what else might they try?