Phalaenopsis with yellowing leaves!!

[chandraluna]

Please help!

I have read the books and don't know what's going on with my phalaenopsis amabilis and other phal....please see photos of leaves...they live in my East facing home office room and receive light and I have a fan for circulation.

My phal amabalis has two plants in one pot and both plants had multi stems with many blooms/buds when I bought it. It has been green and well and after the blooms were finished, cut it at the noids and it started to bud again. As the photo shows, one has spikes and buds.....

The plant that has the yellowing leaves has one spike that seems to be growing from the noid.....

It is planted in orchid mix bark and I've taken care to do my best not to overwater but this strange yellowing, dimpling of the leaves....don't know what this is....!!!

HELP!!