phalaenopsis cell damage

[djm]

Hello everyone,
I am writing because I would like to have your point of view on what is happening to my orchid.

i have about 15 phalaenopsis, some have dehydration issues but everything under control. The are in a sort of little "attic"m with 2 windows on the ceiling to maximize available light; they have "sun-protection" curtains, that protect from direct light leaving all the brightness coming in. The ones with dehydration are out of the potting media, hanging under an open plastic bag, hanging with tray of water underneath. I brought them few steps downstairs as the air might become too dry sometimes up in the attic.

So, this is to have a mental picture of what is the environment.

I spend almost every day some time with my plants, and one day I saw one healthy plant showing the upper (newer) leaf with a yellow stripe in the middle. I thought that maybe a ray of direct sunlight reached her for some reason. I moved her a bit away from the others. In about 2 days, the leaf was completely yellow and dried out. I saw light damage before, and this was too fast...
I cutted it with sterile scissors, and kept an eye on her.

A couple of days afterwards, the biggest leaf right below the one that died started to show unusual sign of sickness. It started to turn yellow in the middle, then cells started to collapse, and some areas turning brown-ish. I will attach pictures. In few days, half of the leaf looked like it had an herpes: all "bubbly", half necrotic. by that time, the plant was isolated in a corner trying to give enough light but stay away from others. I pulled her out of the pot: no issues on the roots.
As I had one of the new plant with some white fungus, I sprayed the sick leaf (well the all plant..) with anti fungal, but noting. The "thing on the leaf kept going". Last night decided that, even if it hurts my hearth to do it, I'll cut the leaf because if it is an infection better lose a leaf than the plant. Felt like a surgeon: gloves, sterile cutter, cinnamon if needed for root inspection, dedicated tray to work on, bag for possible contaminated media to throw away...

......but I believe that the infection spread to the other leaf as well, as the are showing little sign of this "herpes".. I am feeling so bad, this plant was perfectly healthy, the flowers were time ago cutted to let her recover in the new environment, and now she has a new flower-bud coming out!!!

I do not know what to do. I do not know what it is. I have not seen anything like this ever, even online....

If any of you had similar experience please share it with me...

Thanks a lot,
DJ