Dendrobium Nobile cane discoloration

[Irisha99]

Hi, guys.
So this dendrobium Nobile was potted in some kind of wet soil medium that I posted pictures of here a week ago. It was recommended to repot immediately even though it was blooming. I did repot it but just noticed that one of the canes has this brownish green discoloration. The cane feels softer than the other one next to it. It’s rotting? Do I cut it off? What did I do wrong?
I watered it maybe once since I repotted. It’s standing on a windowsill, radiator is below it. Window is covered by parchment paper, so there is no direct light. Temperature in the room is 69F humidity about 23%. I live in nyc so it’s pretty freezing outside. Suggestions? Thanks