Hi!
If this was my plant I think I would repot. This way you can see the extent of the damage and give it new medium. I'm suspecting that if the medium is soggy it has broken down too much. Seeing the size and age of the plant it's possible that it hasn't been repotted in a while. Cym's like to be pot bound, so maybe it should be put back in the same pot. Depends on the roots as well.
When I got my cym nearly 3 years ago I repotted in right away because it was going to explode the pot it was in and there were many dead roots. Now it's doing wonderful,(but no blooms)
and I will probably repot it again after it blooms in late winter.
Szia (hope that's right!
)