Angela, could you post a picture? Yellowing leaves can also be a symptom of sunburn.
I'm a little weary of store-bought orchid mixes...had the same mix as you at one point and almost whipped out all my orchids that were planted in it.
You mentioned bamboo skewers to check humidity? How is this working so far? I know there is a new Momet Water Sensor out there specifically for orchids, I think they had it at Orchids Limited?
Anyhoo, a
would be absolutely wonderful to help pin-point a more specific cause.