My leaf is yellow and floppy...

[annehylee]

Hi Hi! It's been a while since I've been on the orchid board - have been having some problems with my computer. Anyway, glad to be back.
I noticed the other day, the top leaf (which used to be very strong and rigid) is now super floppy... The underside of the leaf has this browny/burgundy colour around the edges and throughout the leaf... It's scary cause this leaf used to be sooo strong and bright green and now it's bent in half all flopped over. Plus, on the same pot, on the leaf underneath, on the other side is yellow at the base... is this a rot?