Very scary reading especially as in light of the problems I've started having with my left forearm. I'm fairly sure it's been caused by practising the flute for too long at one time & not stopping when i felt the first twinges of pain (how stupid was that).
I know I should rest it but that's very difficult when you have an exam less than 3 weeks away. As I see it the options are:
Play for very short periods of time to try & keep everything going if no more than that.
Don't play at all for x number of days until it improves.
Do the exam if I can for experience of performing if nothing else. Accept that it isn't going to be the best it could be -or cancel the exam if needs be.
The worry is that playing at all may make it into a worse problem in the long run.

Also I am supposed to be accompanying some exams & I can't really practise the piano either.