Here is a picture of the orchid. I couldn't get the roots because I didn't want to disturb it more than necessary. When I repotted it 2 weeks ago the roots looked fine.
Is it potted in straight sphagnum? Or the sphagnum is just on the surface?
It seems to be potted too deep. The rhysome must be barely under the surface.
My guess is that the roots are not OK. I would depot it and check the roots.
if you used a much larger pot than it was in previously - it could have been over-watered if you continued to water the same - bigger pots = more media = slower to dry
I'd definitely check roots - repot into a smaller pot