Bagged Phalaenopsis getting yellow spike

[Linn]

Hi, yes I sprinkeled cinnamon on it, because it had a few black spots on the leaves so I worried it was getting fungus there too and I read in another place of someone who did that. But I potted it again earlier today, and I washed off the cinnamon at the same time. Thanks, I didn't know it had a drying effect, I'll stick to put it on the cut parts another time (though I hope there won't be more...).

What is the skewer method?
Should i still keep it in the tent now after I re-potted it?
I'd like to try the perlite, but I'm not sure where I can get it. Would Leca work the same way? Would it be too stressful for it to be put in a different medium again so soon after re-potting it?