I hurt my wrist due to a lot of writing in my geography exam?

I still have one GCSE exam left and it's probably the most intensive in terms of amount of writing (you're constantly writing and you're forced to do it fast as you only have 50mins). I really hurt my wrist muscle in my geography exam and I need tips on what I can do to help it recover. I can still write, but when I do so I gradually feel the pain coming back. Ice? Hot water? What do I do?