Bagged Phalaenopsis getting yellow spike

[Linn]

I've been overwatering my Phalaenopsis and it lost most of its roots, so I bagged it, or rather, I made it a plastic tent with water in the bottom that doesn't touch the plant. I haven't had the chance to get some Sphagnum yet. I've had some problems regulating the humidity and temperature. At first it got some white fungus on the roots and got very warm in there now that its summer. So I made an opening in the top to make some air flow. Then I thought it looked too dry, so I've been spraying it with water.
It has one flower, but the spike is turning yellow in the top and it's gradually spreading downwards. Any idea why? And what should I do? Cut it off?