Market65

Might be worth testing a couple of different design keyboards? Some take more pressure or movement to actuate the keys - it might be only a small difference, but it might be just those repetitive small movements that are causing the problem.

Or change your chair/stand at your desk? Sure you've been told all that already if you've got help.

Mind you, I've never got on with those mad-looking split ergonomic keyboards, e.g. https://www.rsi-shop.co.uk/browse_category.asp?tag=keyboards-split&item=Split+Keyboards

It's a miserable complaint, and one which seems to have become more widespread; next time you go to the supermarket, see how many of the till operators have support bandages from their lower arms to their knuckles.

It would be worth getting a wrist-rest (gel-filled) to support your wrists when using the keyboard. 

Though it seems strange, your general posture, most noticeably how you hold neck and shoulders, can manifest itself as problems with either wrists or elbows (we found this out the hard way; my wife had both Golfer's and Tennis Elbow on both arms, and narrowly escaped surgery.)

She recommends having a look at:-  http://www.hse.gov.uk/msd/dse/assessment.htm and  http://www.hse.gov.uk/pubns/ck1.htm

Her earlier experiences have led her to get involved with work-station design for control centres, so some good came out of it all.