Hi again
Good clear photo's
I forgot to ask you ... What kinda media is your Den potted up in?
The leaves look abit dark in color for a Den, adding more light might be a good idea, these guys love TONS of light.
You can take a very soft tooth brush with some dish soap - 1/2 teaspoon, add water to 1 liter and spray.
You might wanna get a smallish paint brush and get that dust off your leaves too - Uhh reminds me to do my own tomorrow
Then perhaps spray and tooth brush your orchids clean.
If you increase the air movment you really shouldn't see those black spots.
The yellowing could be a root problem, possible a lighting problem?
The leaves will go soon enough, but it's a bit soon, the plant is in flower!
Do you see any new growth at the base of your orchids?